One of the radical attempts to solve the problem of the relationship between science and metaphysics on a non-positivist basis has been undertaken by Karl Popper, a prominent English philosopher, who proposed a doctrine of the structure and development of scientific knowledge and gave it the name of “critical rationalism”. It is noteworthy that the main principles of his doctrine, alternative in a way to logical positivism, were developed by Popper within the walls of its citadel—the Vienna Circle. The ideas of Popper who had been a member of this circle from its very foundation foreshadowed, as it were, the inevitable crisis and disintegration of the new school long before it reached the peak of its glory when nothing seemed to betoken the impending end.

From the very beginning Popper was a severe critic of the new trend in the philosophy of science which was budding within the Vienna Circle among the philosophers and natural scientists interested in the logic and methodology of science. However, Popper was no alien in this circle, though there is an obvious tendency now to leave this fact out of account in considering his relation to logical positivism. Popper’s alliance with the new school was by no means accidental even if we put aside his formal membership of the Vienna Circle. One could evidently speak of a certain difference of opinions concerning the means, yet the aim as such was undoubtedly common. This is true at least of the early period of Popper’s activity when he advocated the restructuring of scientific knowledge on the basis of an empiricist interpretation of its laws and categories and underscored the need for complete elimination of metaphysics from scientific studies. Hence, not only did he identify himself with the tasks set by logical positivism in that early period of his research, but he strove wholeheartedly to solve them in a most consistent and effective manner.

True, the way which Popper considered to be the most expedient and logically sound fell off the tracks chosen by most of the other adherents of the Vienna Circle. Giving him credit for scientific intuition one ought to note that he sensed the inherent weakness of the verification theory when it was still in the cradle and discerned the seeds of contradictions bound to undermine this theory when it was to start revealing its philosophical content, particularly when the principles proclaimed by the Vienna Circle were to be applied to the problems of real scientific cognition.

In his polemics with logical positivism Popper stressed, not without reason, that modern physical theories were too abstract, even speculative, to meet in any degree the criterion of verification. This criterion, according to which the truth of any theoretical statement must be confirmed by direct experience, could not provide reliable guidelines even for a most general appraisal of their scientific value. All attempts to reduce them to experimental data and to show that such statements, if only in the field of classical mechanics, were based on direct observation have proved to be futile. Even the basic laws making the backbone of a theory were too remote from what was called the empirical foundation of science. On the other hand, the treatises devoted to dreams and spiritualistic seances appeared at first sight much closer to everyday experience than theoretical propositions and even seemed to use something like the induction method which held undivided sway in empiricist natural science.

Popper also noted the fact that many scientific theories had originated from myths. It was yet another proof that there existed no sharp demarcation between science and metaphysics, particularly in terms of the verification theory. According to Popper, Copernicus’s heliocentric theory of the Universe was inspired by the neo-Platonists’ worship of the Sun which they placed in the centre of the Universe. Ancient atomistics was another example of a myth that played an extremely important role in the development of science. As opposed to logical positivism which reduced the difference between science and metaphysics to the difference between meaningful and senseless propositions, Popper underscored already in his first mature works that the problem of meaningfulness and senselessness was a pseudo-problem. Metaphysics, according to Popper, was neither a science nor a set of nonsensical assertions. Hence, already in the early period of his ideological evolution Popper held a different view of metaphysics than the founders of the Vienna school influenced to a considerable extent by Wittgenstein’s and Schlick’s ideas.

According to the “verification version” of logical positivism, the criterion of the scientific value of different forms of human knowledge is their confirmability by inductive methods: an assertion can only be regarded scientifically (empirically) valid if it can be confirmed by inductive methods or an inductive inference. [1] As regards a theoretical proposition, it must permit logical reduction to a protocol statement confirmable by an experiment. The basic distinction of Popper’s criterion of scientific knowledge from the verification principle consisted in that he regarded refutability (or “falsifiability”) and not confirmability as the main characteristic feature of a scientific statement. Hence, Popper’s solution of the problem of demarcation between scientific and non-scientific assertions is the direct logical opposite of the neopositivistic criterion. The immunity, even if only thinkable, of a proposed hypothesis against refutation is a sure sign of its metaphysical nature. A system of assertions can only be considered scientific if it is at least capable of being at variance with observation. From this it follows that the verifiability of a theory coincides not with its confirmability, but with its refutability, and this is just what makes the difference between science and “nonscience”. For instance, the existence of God, according to Popper, is asserted in approximately this form: God is because he is. Since this statement is practically tautological, the degree of its confirmability is very high. Yet it is quite obvious that a statement, of this kind is completely immune from refutation and is, therefore, non-scientific.

Popper’s argument against the verification principle and in favour of his “falsification” criterion are serious enough, though not at all as original as he claims. Putting aside the author’s pretence, let us take a more close look at his arguments against the “verification version” of anti-metaphysical philosophy.

First, Popper contends that observation is always preceded by certain theoretical assumptions and scientific knowledge, contrary to the positivist concept, does not start with sensory experience. Second, the traditional problem of empiricism, that of the substantiation of the inductive conclusion, derives, according to Popper, from Hume’s error concerning the nature of the scientific method. In Popper’s opinion, Hume indeed showed that a theory cannot be ’deduced logically from observation statements, yet he overlooked a very important circumstance: his arguments do not prove that a theory cannot be refuted by observation. Therefore, contrary to the expectations of the positivists, empirical generalizations are immaterial for scientific cognition. A scientist is usually not guided by generalised observations, but makes a resolute step and puts forward bold proposals which are subject to subsequent empirical verification. Popper maintains that scientists test new theories not in an attempt to deduce them from a certain imaginary basis, but by creating experimental situations whereby they try to refute or falsify them.

One cannot but admit that Popper did pinpoint the vulnerable spot of empiricism. Yet the full significance of his criticism can only be assessed in the light of the programme which he proposes as an alternative. It may seem at first sight that his epistemological principles are radically different from those of positivism. Indeed, according to Popper, “knowledge cannot start from nothing—from a tabula rasa—nor yet from observation. The advance of knowledge consists, mainly, in the modification of earlier knowledge. Although we may sometimes, for example in archaeology, advance through a chance observation, the significance of the discovery will usually depend upon its power to modify our earlier theories.” [2]

Refutation in science, according to Popper, is a motive force of progress—a refuted hypothesis gives place to another one intended to eliminate or avoid the error. Some conclusion ensuing from an adopted theory or from a hypothesis may be refuted—this will cause the scientists to improve and transform the theory or the hypothesis. It may also happen that the very premises of a theory will prove to be invalid—in that case the theory should be resolutely rejected. In any case, a scientist himself must always strive to subject his hypotheses to severe criticism as it stimulates continuous progress of science. “Refute!” —calls Popper on scientists. A refutation, in his opinion, is a scientist’s victory since any act of rejection represents the essence of sciencof elimination of errors and perpetual progress e: knowledge.

According to Popper, the test of a theory amounts in fact to an attempt to refute it, and refutability is the fundamental property of scientific knowledge, whereas the critical spirit is one of the basic characteristics of scientific life, the ethical imperative, so to speak, of a scientist’s behaviour. In assessing a hypothesis a scientist should first of all decide whether it lends itself to a critical examination and, if so, whether it is capable of withstanding a critical charge. Newton’s theory, says Popper, predicted a deviation of the Sun’s planets from Kepler’s orbits owing to their interaction and thereby exposed itself to a possibility of being refuted by experience. Einstein’s theories were tested in a similar manner as the conclusions they suggested did not follow from Newton’s theory.

By contrast with the metaphysicians striving for an ever broader generalisation and confirmations of their ideas, the scientists do not seek a high degree of probability of their assertions or, to be more precise, it is not their main aim. The more a statement asserts, the less probable it is, says Popper. For instance, a theory giving exact quantitative predictions in relation to the splitting of lines in the atom emission spectrum under the influence of magnetic fields of different intensity is more vulnerable to experimental refutation than a theory predicting merely the effect of a magnetic field on such emission. In that respect, according to Popper, the more definite and refutable a theory is the more verifiable it also is, as it lends itself to more accurate and exacting tests. In other words, contrary, for instance, to Carnap, Popper maintains that a high degree of verifiability cannot represent the aim of science. If that were so, the scientists would confine themselves to tautological statements alone. Actually, however, their task consists in developing science, i.e. in enriching its content, and that is bound to lower the probability of its propositions.

As we see, Popper presents rather a dramatic picture of the evolution of science which consists essentially in a continuous struggle of theories and in the survival of the fittest. Unlike Carnap who regarded the victory of a theory to be in no way damaging to the prestige of its rivals, Popper maintains that the triumph of one hypothesis inevitably spells the doom of all others. With Carnap, scientific theories move in a respectable and civilised society, whereas Popper sees them waging relentless struggle for existence in which the rise of a theory can only be achieved by “murdering” its opponent. Explaining his understanding of the difference between science and “metaphysics”, Popper used to say that a believer perishes together with his false convictions, whereas a scientist sacrifices his creation, a theory, for the sake of the progress of science.

As regards each individual scientific theory, it begins, according to Popper, with a problem. Then follows a tentative solution, a conjecture, criticism and correction of errors. The tentative solution may prove partly or even completely erroneous. Yet this does not mean, says Popper, that a scientist is entitled to a deliberate error. To avoid it, he must, first of all, look deeper into the problem and “comprehend” it. And how can he do this? Popper says: “To understand a problem means to understand its difficulties, and to understand its difficulties means to understand why it is not easily soluble—why the more obvious solutions do not work.” [3] The step that follows a tentative solution consists in discussing and criticising the theory. At this stage everybody tries to find faults with it, to refute it or to correct the errors. Popper writes: “The critical attitude may be described as the conscious attempt to make our theories, or conjectures, suffer in our stead in the struggle for the survival of the fittest. It gives us a chance to survive the elimination of an inadequate hypothesis—when a more dogmatic attitude would eliminate it by eliminating us.” [4]

This attitude, according to Popper, is true of the animal, pre-scientific and scientific knowledge and, consequently, characterises the mechanism of its evolution in general. A specific feature of scientific knowledge consists in that the struggle for existence in human society becomes more difficult because of conscious and systematic criticism.

In Popper’s opinion, one can only speak of any progress in science (as well as of the demarcation line between science and metaphysics) in connection with the possibility of falsification. Popper’s falsification concept is closely linked with his peculiar notions of the genealogical tree of knowledge. If we take a tree in its natural position, i.e. with its crown up, for a model of the evolutionary process, we shall have, according to Popper, the picture of the development of applied sciences, since they are characterised by the ever increasing diversification and specialisation. Yet to visualise the development of pure knowledge, of fundamental sciences, one should set the tree with the crown down, since the leading tendency in the sphere of pure knowledge consists in the growing integration and unification of theories.

From the epistemological viewpoint, Popper’s concept is different from the traditional empiricist stand only in that it dismisses the question of the source of knowledge, since the logic of a scientific discovery which is what Popper’s epistemology boils down to, does not concern itself with questions of this kind. In point of fact, this question lies on the other side of the demarcation line which Popper draws between science and metaphysics. Yet even within the narrow limits of a purely logical model of the process of cognition Popper’s concept gives rise to serious contradictions. Indeed, in investigating the relation between knowledge in general and a concrete discovery or theory one must answer at least two questions: (1) which element of knowledge and at which stage of its maturity is taken as the basic proposition; (2) which proposition in a given specific case can be confirmed or refuted with the help of an experiment. The second question remains, in fact, unanswered by Popper. As regards the first one, the answer is as follows: the initial, basic propositions are a product of arbitrary convention among scientists. Popper does not deny the connection of basic propositions with experience. In The Logic of Scientific Discovery he writes that the decision to adopt a basic proposition stands in causal relation to our sense perceptions. Experience, according to Popper, can only go to the extent of motivating a decision which is needed for the adoption or rejection of a proposition. Yet any attempt to trace basic propositions to perceptions would be entirely fruitless.

As we see, despite the ostensible opposition to empiricism, Popper’s concept reveals a curious similarity to logical positivism in at least two aspects: (1) in its tendency to limit the subject-matter of epistemology to purely logical problems and to reject some general problems (e.g. the problem of the source of knowledge); (2) Popper, like the leading theorists of the Vienna school, is forced to resort to conventionalism when it comes to explaining the origin of basic propositions, though he substitutes conventionalism “from below” for the traditional conventionalism “from above” used by logical positivism in its attempt to account for scientific laws and theories. Popper’s conventionalism is a result of his far-reaching logicism, leading to the dismissal of philosophical and sociological problems of science as insoluble. The basic propositions introduced by Popper are intended to replace the protocol statements of the Vienna school and differ from them in that they reflect a system of conventional knowledge rather than the transient individual experience.

The rational kernel in Popper’s criticism of the verification theory consists in that Popper considers science as an endless chain of theories that replace one another. He effects a radical change in the traditional orientation of the logical analysis of scientific knowledge. Having started with the investigation into the rules of refutation of scientific theories, Popper made the progress of science the pivotal point of his concept. The problem of the criterion of scientificity now organically merges with the concept of the development of science: crises in science, i.e. the collapse of traditional theories are declared to be inherent in the main postulates of the logic of scientific development. The new logic of science is a logic of scientific discovery, of the radical transformation of the existing systems of knowledge. Popper has shifted the focus of attention from the formal logical analysis of systems and propositions to the problem of the logical reconstruction of historical events in scientific development.

In his person the logic of science has made a step towards the history of science in the hope of creating a new tradition in the analysis of scientific knowledge. New horizons have been opened up before logic both in terms of theory and heuristics. Popper’s logical notions show a clear tendency towards historicism in the presentation of scientific progress. Historical analysis, of course, would have been highly helpful in the solution of such problems as the criterion of scientific theories, the role of philosophical knowledge in the development of science, and many others. But such analysis proved to be beyond Popper’s possibilities. Logicism has got the better of his aspirations.

Development, a traditional metaphysical problem, has also been treated with reference to scientific knowledge by Thomas S. Kuhn, who gave it even a more pronounced anti-positivist turn.

In opposition to Popper, Kuhn put forward a thesis that scientific development cannot be explained by means of rational logical notions in principle. The sharp controversy that was initiated by his book The Structure of Scientific Revolutions first published in 1972 is still unabated centering around Kuhn’s polemics with Popper’s school. This polemics is playing rather an important role in weakening the positions of “critical rationalism”.

A crucial feature of scientific life which, according to Kuhn, was ignored by Popper, consists in the presence of some “dogmatic” elements in the scientists’ work which bolster up their faith in the success of their investigations and help them to persist in their studies without arguing with their colleagues. As distinct from Popper who underscores the significance of criticism in science, Kuhn emphasises the function of dogma in scientific investigation. Contrary to Popper, who avers that bold refutations and tough competition of theories pave the way for scientific progress, Kuhn sees the starting point of progress in a transition from debates and competitive theories to a common viewpoint shared by all specialists.

According to Kuhn, the true creator of science is the scientific community, a group of professionals who decide to adopt a certain scientific achievement or theory as a model and make it a basis for their investigations. No scientific community can start investigating natural phenomena without a definite system of generally recognised notions. Such a system of notions also includes certain metaphysical propositions or models of the type: “heat is kinetic energy of particles making a body” or “all perceptible phenomena are essentially interaction of qualitatively homogeneous atoms in free space”, etc. Within the scientific community a model theory is a paradigm, whereas the study of nature within the framework of a paradigm is “normal science”. If there is a paradigm, the solution of concrete scientific problems resembles the solution of puzzles: the scientist has a model of the solution (the paradigm), the rules to be followed, and knows that the problem is soluble. The conditions being set, his success depends on his personal ingenuity. The secret of scientific achievements lies largely in the self-organisation of the scientific community. No other professional group has succeeded to such an extent in fencing itself off from everyday life and laymen’s questions as the scientific community. To be sure, such isolation can never be complete, yet it is very essential. A scientist always does his individual research with an eye to his colleagues in the first place, whereas a poet or a writer addresses a non-professional audience and depends to a great extent on its appreciation. “Just because he is working only for an audience of colleagues, an audience that shares his own values and beliefs, the scientist can take a single set of standards for granted,” [5] writes Kuhn. He does not even have to select his problems— they themselves are waiting for him.

However, this is only the first stage of the scientific process. The next stage consists in a break-down of old paradigms, a crisis and a formation of a new paradigm. It is a period of extraordinary investigations and controversy leading to the development of the new principles of investigation and to the creation of a new picture of the world. The main task of this period is to select a theory that would play the role of a paradigm. This selection, according to Kuhn, is not a logical problem as it appears to logicians. The criterion for the selection lies in a socio-psychological sphere: the scientific community selects for a paradigm the theory which appears to be best suited to ensure the “normal” functioning of the scientific mechanism. Therefore each critical period gives way to a new upsurge of creative activity and another step forward in the onward march of natural science. To an individual scientist, however, a change of basic theories (paradigms) is tantamount to conversion to a new faith: he feels like entering a new world with entirely different objects, notions, problems and tasks.

Hence, a scientific revolution consists essentially in a change of paradigms. This change does not yield to rational explanation in terms of logic as it is rooted in the professional feeling of the scientific community: either the community possesses the necessary means for solving “puzzles”, or, if such means are not available, the community has to create them.

The main turning points in the history of science are associated with the names of Copernicus, Newton, Lavoisier, Einstein. According to Kuhn, each of these turning points signified that a group of professional scientists had to discard one age-old theory in favour of another incompatible with the former.

Paradoxical as it may seem, Popper’s logical concept of scientific revolutions and of the downfall of famous theories has been constructed on the basis of the same historical material. In this connection Kuhn justly observed that Popper had no reason for characterising all scientific activity in the terms applicable to its rare revolutionary periods only.

The severity of the test criteria referred to by Popper is only one side of the medal, the other one being the tradition of “normal” science, the solution of “puzzles”. Subject to testing is not the basic theory, but the scientist’s conjecture, his ingenuity. An erroneous conjecture is a setback for the scientist, but not for his paradigm.

Popper’s idea of the “elimination of errors” which accompanies a change of theories is yet another concept which meets Kuhn’s resolute opposition. Popper regarded as erroneous Ptolemy’s geocentric astronomy, the flogiston theory, Newton’s mechanics. Kuhn refuses to accept this point of view: no “error” has been committed in the development of these theories and the notion of error in general is absolutely irrelevant in the assessment of an obsolete scientific theory. In his opinion, the most one can say in such cases is that a theory which had once been correct later became erroneous, or that a scientist made a mistake by adhering to a theory too long.

In the final analysis the basic distinction between Popper’s and Kuhn’s concepts lies in their different understanding of the nature of science and progress. Popper has repeatedly emphasised the need to cast off “psychologism” in the solution of such problems. He was never tired of repeating that his concern was the logical rules of scientific progress rather than the scientists’ psychological incentives; yet he could not but admit that the rules of logic followed by scientists in their investigations are something like their professional imperatives. In contrast to Popper, Kuhn contends that such imperatives alone can account for a scientist’s selection of one solution instead of another and that his preference cannot be explained on purely logical or experimental grounds. In other words, it is only the analysis of socio-psychological factors in the development of science that provides a key to the correct understanding of the historical aspects of scientific progress. Popper’s science is impersonal whereas Kuhn strives to introduce a “human element” into the logical problems of scientific cognition and highlights its sociological and psychological aspects. Both concepts, however, are completely divorced from the problem of the interaction between philosophy and particular sciences. Moreover, Kuhn even makes a special point of substantiating this indifference. A question, naturally, arises if such an abstraction in the investigation of the history of science is justifiable and if it is not likely to distort the true picture of scientific progress.

A serious attempt to save the logical tradition in the analysis of historical changes in science was made by Popper’s disciple Imre Lakatos, a prominent representative of critical rationalism and a talented expounder of his school’s principles.

Lakatos holds that it is necessary to discard completely the tradition of logical positivism which focused on formal logical means in the analysis of scientific knowledge. [6] He shares Popper’s opinion that the only way in the investigation of the logic of science is to turn to the real practice of scientific thinking. To substantiate this view he shows that even mathematics which has long been regarded as the main bastion of the adherents of formal logical analysis needs the substantive analysis of its history so as to get a basis for the development of the logical and methodological scheme of scientific discovery.

Each time the historical process of scientific cognition reveals a need for a change in the existing system of knowledge there appears a possibility for different strategies and for different ways of development. Being always faced with the necessity of “casting lots” in selecting one of the alternatives that would prove the most beneficial for further scientific progress, the scientists never stop seeking for a guideline. This guideline, according to Lakatos, must be provided by the modern logic of science. It is precisely for this reason that it should break off with the tradition of formalism. Formal logical analysis deals with deductive, formalised theories which represent science in the artificially “frozen” state, whereas the real object of logical analysis and explanation should be the methods and mechanisms of changes in the structure of knowledge. Criticism gives scientists a rich “situation logic”, i.e. opens up a broad range of possible lines of behaviour in different situations.

Lakatos points out that Popper’s solution of the “demarcation” puzzle and his criterion of scientific knowledge have brought about a radical change in the very formulation of the problem. After Popper, the logical appraisal of a scientific theory turned in fact into the analysis of conditions under which a given theory or hypothesis can be adopted for scientific use. In other words, Popper’s new approach to the traditional problems of the logic of science brought to the forefront the question of the acceptability of a scientific theory or a hypothesis. According to Popper, a theory can only be accepted as scientific if it is falsifiable. Lakatos, however, regards this criterion as only one of the requirements a theory must meet in order to become acceptable.

Kuhn’s controversy with Popper about scientific revolutions raised the crucial question of the possibility of representing the endless change of fundamental scientific theories as a rational process interpretable in terms of logic. As for Lakatos, his main object was to give a logical explanation of the victory of a new paradigm. He is firmly convinced that logic is capable of giving the scientist a rational guideline for his behaviour during a “critical” period in the development of science. Proceeding from this aim, Lakatos develops his concept known as the “methodology of research programmes”.

Lakatos sides with Kuhn in his criticism of Popper’s rule: “having falsified—reject!”. According to Lakatos, the comparison of a theory with the results of an experiment is a more complex procedure than Popper originally thought it to be. This comparison involves, as it were, three “layers” of knowledge: (1) the theory under test itself; (2) the sensory data explained by the theory (for instance, the light images observed with the help of an optical instrument); (3) the so-called background knowledge embodied, for instance, in the instrument design. We cannot know what the experiment demonstrates and how it can pass a final judgement on the theory under test. Rather, says Lakatos, we subject to testing a tangle of our theories and the experiment’s verdict is: “incompatible”. Which of the theories must be rejected is still a big question. Generally speaking, there are no absolutely indisputable facts which would compel an ardent adherent of a theory to surrender immediately and unconditionally. On these grounds Lakatos comes to the conclusion that a theory cannot be invalidated by a single empirical counter-example. Its rejection can only come about in the process of adoption of a new, better theory.

Broadly speaking, it means that the true object of a logical evaluation is a series of theories in their succession rather than an individual theory. Several series cluster around propositions playing the role of something like a dogma—here, according to Lakatos, Kuhn was right. It can therefore be affirmed with good reason that the scientists in their investigations of nature translate into reality some more or less developed “programmes”.

Lakatos understands science as activity aimed at solving concrete problems within the framework of a certain programme. Each programme can be viewed as consisting of two components: a rigid core and a safety zone of “sacrificial” theories. The rigid core consists of one or several propositions which are not subject to refutation. Such are, for instance, the three laws of thermodynamics and the law of gravitation for the adherents of Newton’s theory. These propositions must be preserved under any onslaught of falsifying data. The “salvation” of the core is achieved at the expense of auxiliary hypotheses which replace one another and are intended to neutralise counter-examples and preserve the core with the help of various amendments and modifications.

By way of illustration Lakatos refers to Newton’s gradual elaboration of his theoretical models. [7] Having first worked out his programme for a planetary system with a fixed point—like the Sun and one single point-like planet, Newton derived his inverse square law for Kepler’s ellipse. But this model was forbidden by Newton’s own third law of dynamics, therefore the model had to be replaced by one in which both the Sun and the planet revolved round their common centre of gravity. Later he introduced more planets as if there were only heliocentric but no interplanetary forces. However, the results obtained at this stage ran counter to observations, and later Newton worked out the case where the Sun and planets were not mass points but mass-balls and also introduced interplanetary forces. Such multistage elaboration, according to Lakatos, reveals the true course of the scientist’s thought.

The history of science, according to Lakatos, is the history of the birth, life and death of research programmes. While a programme is being realised, science runs its normal course—it is Kuhn’s “normal science”. During a change of programmes, or a change of paradigms, science undergoes a revolution. As distinct from Kuhn, however, Lakatos believes that programmes are logically commensurable and can be compared to one another. Their comparative analysis can provide a scientist with a reasonably reliable guideline for selecting one programme and rejecting another.

According to Lakatos, any theoretical concept of knowledge provides a framework for the rational restructuring of the history of scientific knowledge. Though not every detail in the history of science fits in with rational explanation, logico-methodological concepts should provide the closest possible approximation to real processes in order to permit their description. For instance, an inductivist who considers Newton’s theory an “error”, and its lasting prevalence a delusion would find no rational justification for it. Popper’s type of logic would provide a rational explanation for a scientist’s failure to recognize the collapse of his theory by referring to his metaphysical views. In Lakatos’ opinion, preference should be given to a concept which permits the rational restructuring and interpretation of the largest possible number of facts in the history of science. Proceeding from this criterion, Lakatos considers his concepts to be the most expedient. However that may be, his ultimate conclusion is this: it is the history of science which is the touchstone of any logico-methodological concept, its strict and uncompromising judge.

The controversy between the “critical rationalists” and the adherents of Kuhn’s-concept of the history of science had greatly affected the assessment of the very possibility of constructing a purely logical concept of scientific knowledge and its development. The most sceptical views in relation to this problem were expressed by Paul Feyerabend. In one of his works, after expounding the basic principles of Popper’s logic of scientific investigation, Feyerabend puts two questions which he considers to be of prime importance: (1) whether it is desirable to live up to the rules of “critical rationalism” and (2) whether science can be brought in accord with these rules. [8] Feyerabend gives negative answers to both questions.

According to Feyerabend, the highly specialised thinking characteristic of modern civilisation is accountable for a corresponding narrow approach to the study of man’s cognitive activity and for a tendency to rationalise the process of cognition by simplifying its participants, strictly delimiting the field under investigation and by abstracting from historical context. Feyerabend contends that such abstraction from the external factors of scientific development becomes fatal for philosophy, since human inclinations, interests and ideological influences have a greater effect on the progress of knowledge than is generally believed. Despite his general opposition to Kuhn’s understanding of the nature of scientific activity, Feyerabend, as he himself admitted, had wholeheartedly accepted his thesis of the incommensurability of basic scientific theories that succeed one another in history. Incommensurability was the point on which the views of both authors completely coincided when they were discussing the basic ideas of Kuhn’s book. Kuhn was fond of comparing the world as it appeared to Aristotle with the world depicted by the 17th-century science. Having taken the cue, Feyerabend carries out a detailed comparative analysis of classical celestial mechanics and the special theory of relativity and strives to show that even the concepts of length, mass and speed in these theories were entirely different. According to both Kuhn and Feyerabend, the meaning of observation terms is completely determined by the theoretical context in which they are used. From this it follows that theories replacing one another are mutually incompatible and even incommensurable. They belong to different worlds. The field of application of a new theory is not necessarily the extended field of application of the previous theory, these fields may only overlap each other. The view according to which a new theory is bound to be commensurable with the previous one cannot be accepted as a universal principle. Incommensurability may be eliminated in one aspect, but holds good or even becomes more complete in another.

The thesis of the incommensurability of theories succeeding one another is so important for Feyerabend that he considers it imperative for the logical analysis of scientific theories to start with revealing and emphasising the qualitative distinction of the new theory over the old one. A new theory must not only explain new facts, but also show the causes of the failure of the old theory. It is only on this condition that a new theory can be admitted to the temple of science. According to Feyerabend, a scientific theory can only be identified by its novelty and complete break from its predecessor. This criterion should also be applied to epistemology and to the logic of science.

Feyerabend contends that the history of science testifies to the absence of any norms and standards of scientific activity valid for all times. Proceeding from his own understanding of Hegelian dialectics, Feyerabend maintains that any phenomenon can only be investigated in terms of the dialectics of the subjective and the objective, chance and necessity. Any absolutisation of norms and rules tends to bar the way to cognition. The true task of philosophy is to neutralise the baneful trends towards the stability and rigidity of methodological norms. Philosophy should embody the whole gamut of man’s creative potentialities, all his individual qualities. To achieve this end, however, it must do away with the stability of all norms of scientific knowledge. Consequently, the logic of science should renounce the very idea of standards which hold good throughout history. Such standards can at best be treated as a verbal ornament or, more accurately, as a remembrance of those happy days when it was believed possible to gain success in science just by observing a few simple and rational rules and when scientific investigation was not yet known to be a risky and hazardous venture that it is, with endless upheavals and cataclysms.

Feyerabend’s methodology calls for rejection of the theoretical monism characteristic of positivist and some other philosophical doctrines. The plurality of theories, in his opinion, must not be regarded as a preliminary stage of knowledge which will be replaced later by a “single true theory”. “Theoretical pluralism is assumed to be an essential feature of all knowledge that claims to be objective,” writes Feyerabend. “Nor can one rest content with a plurality, that is merely abstract and created by arbitrarily denying now this and now that component of the dominant point of view, as is the plurality created by the various attempts of modern artists to free themselves from the conventions of their predecessors.” [9]

In its methodological orientation the theory of science should proceed from the idea of epistemological anarchism. The development of science, according to Feyerabend, is a process of the continuous combination of standards and their violations, dogmas and heresies, norms and errors. Kuhn’s “normal science” does exist, but it has to be opposed in every way as it reflects the ideology of professional specialist. Kuhn’s concept of paradigm is deficient in that it “consoles” the specialists instead of subjecting their views to criticism. Feyerabend’s motto is an uninterrupted revolution.

Proceeding from his own interpretation of Hegel’s words about human practice, man’s spiritual and practical activity, Feyerabend avers that it excludes any regularities. A theory of science should only provide some general hints, rules of thumb and heuristic methods, but not general injunctions. “Knowledge is ... an ever-increasing ocean of mutually incompatible (and perhaps even incommensurable) alternatives.” [10]

Nor is philosophy itself amenable to rational analysis in view of the disorderliness, complexity and wholeness of its structure.

Feyerabend proposes a broad programme of struggle to attain the ideal of anarchic epistemology and overcome the ideas of critical rationalism which seeks to alienate science and enslave human spirit. He points out three means to achieve this goal: (1) scrupulous analysis of the works of such revolutionaries as Galilei, Newton, Luther, Marx and Lenin; (2) study of Hegel’s philosophy and its alternative as.expounded by Kierkegaard; (3) integration of science and art. According to Feyerabend, their present separation is not natural and results from the idea of professionalism which must be discarded. A poem or a play can be intellectual and informative in equal degree (Aristophanes, Brecht), whereas scientific theories are capable of giving pleasure (Galilei, Dirac). In Feyerabend’s opinion, we can change science and make it conform to our tastes.

Being indeed anarchical and wide open to all winds of theoretical thought, this model of scientific knowledge nevertheless leaves enough room for metaphysical ideas. Moreover, their function, as defined by Feyerabend, makes them a decisive factor both in the criticism and in the development of what is generally believed and “highly confirmed”. Hence, they must be present at any stage of the development of scientific knowledge. Feyerabend contends that a science free from all metaphysics is on the way of becoming a dogmatic metaphysical system. Metaphysics performs the role of an instrument of criticism of existing theories, on the one hand, and, just because of the possibility of such criticism, is an argument in favour of these theories. The postulate of Feyerabend’s philosophy affirming the absence of any certainty, stability and system in methodology assumes itself the character of a dogma. Its absolutisation results in the restoration of a new variety of metaphysics which is anything but refined.

Joseph Agassi also shares the view that the claim of logic to the role of the theory of scientific knowledge can hardly be considered justifiable. As for himself, he is inspired by the idea of reproducing the real history of science with all its wealth of conflicting tendencies, and the methodology of science has no special appeal for him. The keynote of his works is the futility of preconceived viewpoints and the need for a scrupulous and unbiased reproduction of the entire history of science with all its real conflicting tendencies.

In Agassi’s opinion, one ought to start with asking himself a question: what do we know about science in general and about its history? The existing historiography is too raw to provide a basis even for a most abstract theoretical discussion of the criterion of scientificity and the logical principles of cognition.

Agassi contends that a broad programme of historiographic investigations of science should be based on Popper’s situation logic which makes it possible to reveal the historical context of various scientific theories or hypotheses. He warns, however, that such investigations should not be influenced by any preconceived idea of science, since the present-day task consists in disclosing and singling out concrete genetic links between scientific theories rather than in their reduction to some ideal type or logical model.

Agassi holds that the core of science reveals itself in the scientists’ “metaphysical”, i.e. philosophical, views which should therefore be given priority attention in historiographic studies. He shows that philosophical ideas tend to degrade to current opinions if their authors are shy of exposing them to criticism. Those and only those scientists can develop new fruitful theories who are willing to subject their philosophical principles to a serious examination. According to Agassi, the priority objective of a historian of science is to disclose the nature of the metaphysical nucleus of scientific theories and doctrines. He therefore contends that there should be a radical change in the very orientation of the logical analysis of knowledge which, in his opinion, should be focused on historiographic investigations. The history of science should be written anew, since the existing historiography of science is unsatisfactory.

It is evidently for the accomplishment of this task that Agassi sets out to revive metaphysics.

Significantly, Popper, Feyerabend, Lakatos and some other representatives of the modern philosophy of science follow different paths and are interested in different aspects of scientific cognition. Yet they have one point in common— all of them stand for the rehabilitation of metaphysics which has been held in contempt by positivism for many years. Of course, the difference in their approach to the process of cognition and their different aims cannot but tell on their concepts of metaphysics, their understanding of its role in scientific cognition and their attitude to traditional philosophical problems. For instance, unlike Popper who does not go beyond the formal justification of metaphysics, and unlike Lakatos who confines himself to asserting the irreducibility of theory to the empirical basis, Agassi’s doctrine tends to endow metaphysics with certain substance.

Accepting in principle the view that metaphysical proposition can be identified by its empirical unfalsifiability, Agassi nevertheless brings his metaphysics closer to the traditional philosophical problems. It is indicative that his assessment of the scientificity of one or another theory depends to a certain extent on its relation to metaphysics. Thus the selection of scientific problems which are to be studied should be governed, according to Agassi, not by the degree or their verifiability or falsifiability, but by their importance for arising metaphysical problems. Metaphysics is regarded by Agassi as a coordinating factor in the development of science, since the criterion of the importance of a scientific problem is its metaphysical significance.

It is noteworthy that Agassi’s understanding of the concrete historical conditions affecting the development of science appears to be more profound than that of Popper, as he takes into account or, at least, shows interest in the factors determining the selection of problems to be tackled and the change of scientific interests (including the change of “vogue” in science). An important role, in his opinion, belongs not only to the techniques and equipment used in experiments, but also to the general socio-economic situation, to society’s needs, etc. For all that, his doctrine assigns the role of the main factor to none other than metaphysics. “Some scientific problems,” he writes, “are relevant to metaphysics; and as a rule it is the class of scientific problems that exhibit this relevance which is chosen to be studied.” [11]

In his analysis Agassi deals not so much with a single theory as with a totality of theories, problems and methods of investigation characteristic of a given period and viewed by him as a single whole. It enables him to make comparisons and deduce general principles governing scientific progress in different fields, e.g. in physics, biology, social sciences in a given period. In Agassi’s interpretation, metaphysics is no longer a specialised theory divorced from science. Hence, the focus of attention should be shifted from the problem of demarcation between science and non-science to that of demarcation between science, on the one hand, and metaphysics (bad or good), on the other.

This leads to a corresponding modification of the criterion of such demarcation: the aim of scientific investigation, according to Agassi and contrary to Popper, is not to find and verify plausible hypotheses, but to search for and to test those hypotheses which appear to be relevant to metaphysics.

Reasoning in a purely metaphysical manner, Popper regards the transition from observations to a good theory not as a result of some inductive conclusion, but as a tentative solution subject to testing, as an advancement of any new theory. The criterion of a theory which is to be given priority in testing should be, according to Popper, its falsifiability. Contrary to Popper, Agassi contends that the choice among rival theories should be made on an heuristic basis and governed by metaphysical considerations. He also contends that metaphysics itself takes part in the development of theories considered important in given problem situations. “Scientific physics,” he writes, “belongs to the rational debate concerning metaphysical ideas. Some of the greatest single experiments in the history of modern physics are experiments related to metaphysics. I suggest that their relevance to metaphysics contributes to their uncontested high status. And yet, I contend, the metaphysical theories related to these experiments were not parts of science.” [12]

Metaphysics for Agassi is not something homogeneous. As has been indicated above, it can be “bad” or “good”. The former merges with pseudoscience, the latter, with science. Bad metaphysics, such as existentialism or Hegel’s philosophy is not capable of exerting serious influence on the development of science. Good metaphysics, on the contrary, not only provides something like a methodological programme for science— in point of fact, it blends with science and can hardly be distinguished from it.

Agassi regards metaphysics as a programme for future scientific development and stresses that it cannot be characterised as “true” or “false”— it can be either commendable or condemnable. Here Agassi practically follows in Popper’s footsteps adopting the main principles of his doctrine. Metaphysical theories themselves may engender an attractive programme such as that of Faraday, but the attractiveness or unattractiveness of a programme is not directly connected with the truth or falsity of the metaphysical theory that produced it. According to Agassi, the significance of a programme is only determined by the heuristic value of this theory. At this point, however, we arrive at a contradiction: if the criterion of demarcation between science and metaphysics holds good, the truth or falsity of metaphysical theories will not depend on their refutability, or else there must exist a method for establishing the truth or falsity of theories without resorting to their falsification.

In his concept Agassi strives to fence off “bad” metaphysics which claims to be on an equal footing with empirical science. He says: “Metaphysics may be viewed as a research program, and the false claims of pseudo-science as the result of confusing a program with the finished product.” [13] Yet he fails to draw a distinct demarcation line between true science and the pseudo-scientific style of thinking characteristic of old natural philosophy. Unlike Lakatos who either merges metaphysics with special sciences and practically makes it their integral part, or altogether eliminates metaphysics from scientific investigations regarding it as some obscure source of inspiration for the scientist, some purely subjective factor akin to his personal inclinations, aesthetic tastes or peculiarities of biography, Agassi strives to resolve the contradiction by turning this subjective factor into something immanent in the very substance of science. A scientific theory in his doctrine appears as some kind of interpretation of a metaphysical concept, but not as its logical consequence.

It should be rioted, however, that this part of Agassi’s programme of reviving metaphysics is patently beneath any criticism. What with metaphysical theories being neither true, nor false, there remains at best but one way out: to assume that there are no practical means, or even no possibility in general to come to a definite conclusion as regards their status. In that case, however, one has to give up all attempts at distinguishing between metaphysics and science and to leave the reader in the dark regarding the ways whereby metaphysics becomes immanent in scientific theories undergoing strict verification procedures. It proves impossible to reconcile the understanding of philosophy as an external factor determining the development of science with its role of an internal factor determining its content. The sphere of metaphysics, too, though including some traditional philosophical problems, appears to be both too narrow and too vaguely defined for all Agassi’s pretensions to having developed a highly efficient working model, something like a matrix for production of new theories. All that a scientist now needs, according to Agassi, is but a few comparatively simple parameters having a purely “technical” meaning. In Agassi’s doctrine metaphysical propositions have no basic distinctions from empirical generalisations. On the other hand, they must meet the rigid rules of formal logic. This kind of approach which appears more or less compatible with Lakatos’ concept does not tally with Agassi’s historiographic orientation and runs counter to his intention of giving a sufficiently accurate, adequate and broad representation of the historical process of scientific cognition.

The history of “critical rationalism” shows that Popper’s initial call to.turn to the analysis of the development of science has proved, as it were, a Trojan horse for critical rationalism. Having taken his cue from Popper, Feyerabend comes to doubt the very possibility of maintaining a logical, normative stand in the analysis of scientific knowledge. The criterion and the norms of scientificity advanced by critical rationalism prove untenable when applied to the real practice of scientific thinking, to the study of the history of science. As a result, Agassi puts forward a new programme of the investigation of science focusing not on the logic, but on the history of its development.

Would it be correct, then, to draw the conclusion that the history of science indeed attests to the fallacy of the existing logical concepts of scientific knowledge and its development? It would rather be more correct to say, paraphrasing Lakatos, that life itself has compared the logical and historical pictures of science and showed that these pictures are “incompatible”. Hence, the conclusion of the “critical rationalists” about ’the necessity of radical changes both in the history and logic of science appears to be quite sound.

“Critical rationalism” is undoubtedly one-sided in all its variants of scientific development as it does not strive to present science as an integral part of the life of society. Yet this school has succeeded in showing one important thing, namely, that the progress of science is not a simple accumulation of knowledge or a gradual increase of its certainty, but a complex contradictory process.

The positivist logic of science was only capable of reflecting the norms and standards of a certain “synchronous” level of science. “Critical rationalism” has made an attempt to construct a logic of scientific development, i.e. a logic capable of reflecting “diachronous” transformations. This attempt, however, has called in question the very idea of such a logic. Indeed, the history of “critical rationalism” has vividly demonstrated that the traditional logical approach with its orientation on the “natural” laws of rational thinking suffers a complete fiasco whenever it is applied to the problems of growth and development of knowledge. The “critical rationalists” cannot accept this fact as all of them, even such a radical as Feyerabend, have committed themselves to the logical tradition. Nevertheless, the tendency to tone down the rigours of the positivist attitude to “metaphysics” and to link philosophico-methodological analysis (without reducing it to sensory experience) with the 20th-century theoretical investigations clearly revealed itself already in Popper’s early fundamental works. This tendency became even more manifest in his subsequent studies and particularly in the investigations of other “critical rationalists”. Popper’s concept of science as a chain of successive theories replacing one another accounts to some extent for an important change in the traditional positivist orientation of logical analysis. Starting out with the doctrine of falsification, Popper has come to the problems of the development of science and reassessed the criterion of scientificity in terms of historical progress. Crises in science, i.e. the periods of the collapse of its traditional theories, are not only explained by his logic, but ensue from its main postulates. A theory which is found to be fully confirmable turns, according to Popper, into technology, know-how or something of the kind and has no more room in the temple of science.

Popper’s logic of science is the logic of scientific discovery, the logic of a radical transformation of the existing system of knowledge. His emphasis on the history of science is an important point of his programme of logical analysis marking a considerable deviation from the positivist traditions if only for the fact that he focused his attention not on the formal logical analysis of systems of statements, but on the problem of the logical representation of scientific development. To be sure, his emphasis on the relative independence of theoretical knowledge afforded greater freedom for creative thinking and allowed for a possibility of generic links between scientific theories. and “metaphysics”. Nevertheless, despite the deductive character of the logical structure of knowledge, Popper’s concept, as has already been pointed out, did not go beyond the limits of empiricism since it proceeded from the direct dependence of a theory on its empirical verification, post factum though it was. This dependence on empirical data was perhaps even more rigid than allowed by the “verification version”. On these grounds early Popper’s concept should be regarded on the whole as essentially logico-positivistic. Its assessment by “critical realism” focusing on the formal structure of Popper’s logico-methodological system rather than on its philosophical orientation need not be taken into account too seriously.

Popper’s attitude to metaphysics, i.e. to general ontological problems, as well as his definition of the falsification principle have been gradually changing. His later works present a modified falsification variant watered down in accordance with his growing interest in metaphysical problems and in the question of autonomy of the so-called World 3. To be sure, from the very beginning Popper’s philosophical system as a whole did not fit the Procrustean bed of the falsification principle devised by him to eliminate “metaphysics” and looked, from the viewpoint of this principle, quite metaphysical even in its initial explication. Yet late Popper’s blunt turn to metaphysics was evidently somewhat unexpected and amusing even for his most ardent adherents despite the obvious trend towards such a development traceable already in his early publications. Popper’s new stand was clearly expressed in his works Objective Knowledge (1972) and The Self and Its Brain (1977) in which he set out to construct a cosmic methodological system, though already in the 1950s and 1960s Popper had criticised the physicalist and behaviourist theories of consciousness questioning at the same time the fruitfulness of the linguistic approach to the problems of matter, spirit, the brain and psychological phenomena.

Popper’s recognition of refutability as a characteristic feature of scientific knowledge and his assessment of metaphysics as a historically inevitable, though mythological stage of scientific cognition were in themselves important steps towards his own “metaphysics”. No less important was his idea that the mysterious process of scientific cognition manifests itself in the strife of hypotheses and theories, i.e. in the sphere of rational thinking, but not in the depths of the scientist’s individual consciousness. This concept was also instrumental in paving the way for metaphysics and contributed to the materialisation of consciousness. All these fragmentary notions developed later into an evolutionary concept of consciousness and knowledge, into a metaphysical system of “three worlds” which shall be considered in more detail in the next chapter.

Popper’s main epistemological or logico-methodological doctrine denies the validity of any final explanations or final truths. Yet Popper abandons his principles when it comes to the primary source of objective knowledge. Rejecting Plato’s metaphysics of ideas, he evolves his own metaphysics which resembles to some extent 18th-century natural philosophy and is supplemented by notions borrowed from evolutionism and genetics. Popper maintains that active human consciousness capable of influencing the environment through the mediation of culture had its forerunner—the biological evolution of organisms. The aims and preferences of the organism influence the environment which, in turn, affects the evolution of the organism. According to Popper, this “emergent” process is not only analogous to the consciousness and vital activity of the organism, but also provides a key to the understanding of the origin of science.

Already in his Objective Knowledge Popper makes an attempt to reveal the embryo of science in its incipiency in the vegitable and animal kingdoms. “I assert,” he writes, “that every animal is born with expectations or anticipations which could be framed as hypotheses, a kind of hypothetical knowledge.” [14] This, according to Popper, is the secret of the phylogenesis of scientific knowledge which provides a clue to its ontogenesis. In his opinion, “this inborn knowledge, these inborn expectations will ... create our first problems; and the ensuing growth of our knowledge may therefore be described as consisting throughout of corrections and modifications of previous knowledge”. [15]

Hence, there is no and cannot be any “exoteric” history of science. Its history is the logic of scientific discoveries which is nothing but a chain of successive problems or theories.

The genetic structure of man also contains in incipiency the faculty of speech which plays an important part in natural selection and, according to Popper, participates in some obscure way in the social process of language study. Thus Popper comes to the problem of the relationship between consciousness and the brain, spirit and matter, not only from the logical, but also from the historical viewpoint. However, handicapped by his earlier commitments, Popper in fact disregards the historical aspect in the development of consciousness and ignores the real, social context of its formation and progress. The emergence of language, according to Popper, leads to the formation of the cortex and, consequently, to the development of consciousness.

Popper’s biological approach to the problem of the origin and development of knowledge prompted by his studies of modern evolutionary biology and genetics must have become yet another stepping stone towards his concept of “emergent realism”. In recent years this concept has been contrasted not only to positivism with its physicalist and behaviourist tendencies in the approach to the problems of the nature of consciousness, history, etc. but also to the ideas of the so-called “scientific realism” and “scientific materialism”. Investigating the origin of objective knowledge, Popper has been engaged of late in a controversy against idealism, phenomenalism, positivism, materialism and behaviourism simultaneously or, using his own words, against all forms of anti-pluralism [16]. Explaining the reason for his critical attitude towards reductionism, Popper describes life as an inherent property of all physical bodies. He declares: “If the situation is such that, on the one hand, living organisms may originate by a natural process from non-living systems, and that, on the other hand, there is no complete theoretical understanding of life possible in physical terms, then we might speak of life as an emergent property of physical bodies, of matter.” [17]

Coming out against positivist reductionism, Popper specially emphasises the uselessness of purely linguistic solutions whereby the behaviour of an individual once explained in terms of postulated psychical states is translated into the language of physiological states, or an account of a physiological state is reduced by linguistic means to the Schrödinger equation. Particularly characteristic in this respect is Popper’s reappraisal of the problems which he recently qualified as metaphysical: “We must beware,” he writes, “of solving, or dissolving, factual problems linguistically, that is, by the all too simple method of refusing to talk about them. On the contrary, we must be pluralists, at least to start with: we should first emphasize the difficulties, even if they look insoluble, as the body-mind problem may look to some.” [18] According to Popper, the hopes that the objective meaning of a theory can be reduced to the states of consciousness of those who propound it rest on a trivial error—failure to distinguish between the two meanings of the word “thinking”. In the subjective sense “thinking” describes perceptions or the processes of consciousness, but different perceptions or acts of individual consciousness cannot be logically related even if they are causally connected to one another.

Another problem which has come of late to be interpreted by Popper in terms of “emergent realism” is the relationship between the self and its brain. Popper agrees with “scientific materialism” in that all spiritual activities of the individual are accompanied by certain brain processes. Yet his concept of the self is entirely different from that of scientific materialism as he regards it essentially as a self-contained entity identical with what was earlier called “soul” and what actually constitutes man’s true essence less the religious envelope. Popper ranks himself among the interactionists who disagree with the materialists in the understanding of the relationship between the consciousness and the brain and regard the problem basically in terms of the interaction between two levels of reality—the psychic and the physical. Moreover, they assign the active role in this system not to the physical world, i.e. the brain as a material object, but to what they consider to be the self. Popper even goes so far as to assume that the self is a quasi-substantial entity if substance is understood as a process or as activity in general.

Traditional materialism, according to Popper, usually linked man to machine, modern materialism identifies him with computer, whereas the self is in fact the ghost in the machine and at the .same time the active programmer of the thinking activity. The self is the embodiment of wishes, plans, hopes, the determination to act and the acute awareness of its being the acting centre. The self is the motive force of activity. What makes the self is different from the chemical and biological processes attending the act of thinking and other kinds of activity by one unique quality— the integration and coherence of experience. Expounding his views, Popper writes: “What characterizes the self (as opposed to the electrochemical processes of the brain on which the self largely depends—a dependence which seems far from one-sided) is that all our experiences are closely related and integrated; not only with past experiences but also with our changing programmes for action, our expectations, and our theories— with our models of the physical and the cultural environment, past, present, and future, including the problems which they raise for our evaluations, and for our programmes for action. But all these belong, at least in part, to World 3.” [19]

The important conclusion that Popper makes reflects the socio-ethical and ideological thrust of his concept: the emergence of the self signifies the transition of nature to a socio-cultural level of development and the transformation of the laws of evolution and natural selection in accordance with the new environment. “The main function of mind and of World 3,” writes Popper, “is that they make possible the application of the method of trial and the elimination of error without the violent elimination of ourselves... Thus in bringing about the emergence of mind, and World 3, natural selection transcends itself and its originally violent character... Non-violent cultural evolution is not just a Utopian dream; it is, rather, a possible result of the emergence of mind through natural selection.” [20]

Hence, Popper’s scheme of cognition, his understanding of its sources and trends is falling under the increasing influence of the concept of natural selection and biological inheritance. It stands to reason that this concept can in no way be subjected to empirical verification. Being a simple extrapolation of biological laws to the sphere of scientific cognition it is postulated as premise which does not have to be proved and is in fact rooted in Popper’s interest in biology. The notions of evolutionary biology are introduced into the system of epistemological categories by analogy rather than on the basis of a serious investigation into the nature of cognitive processes. Biological laws are declared to be universal, governing the development of the world in general and the process of cognition in particular. Popper’s former logicism gives way here to a biologised concept of scientific development which seems to contain more of a substance than a purely formal logical theory. Yet this ostensibly more profound concept is essentially metaphysical, and that in the worst sense of the word, because of its undisguised apriorism, subjectivism and speculative nature.

Rejecting the principle of the universality of physico-mathematical knowledge which underlies the concept of logical positivism, Popper comes in the end, as a result of his own evolution, to the “ontologisation” of biological knowledge substituting biological laws and notions for general philosophical principles and traditional philosophical problems. Using the falsification theory as a foundation, and the notions of special sciences, mainly biology, as building blocks, Popper erects his own metaphysical building that has no room for categories and problems with long-standing historical tradition behind them. Even if he speaks of the active essence of consciousness materialising in culture, i.e. in the universal, and strives to find some culturological approach to the solution of different problems, this approach is limited to the self-programmed wholeness” of “World 3”. As to social reality, it is reduced by Popper to an indefinite combination of “physical reality” and “World 3”.

All in all, Popper’s doctrine with all its weaknesses inherent in any metaphysical system and often justly criticised by both positivists and “scientific realists”, and handicapped by its speculativeness, apriorism, empirical contestability and dogmatism proves rather a meagre replica of more profound systems. It offers but very schematic, embryonic versions of “new metaphysics” which is far behind 18th-century materialistic natural philosophy and Hegel’s idealistic metaphysics in terms of profoundness, informativeness and wealth of concrete material. It is not improbable that the further evolution of “critical realism” and the views of its inspirer, who has evidently embarked on the final stage of his scientific career, will somewhat enrich and elaborate the schematic solutions proposed so far. Yet the very return of positivism to metaphysics, and a crude one at that which aggravates the old weaknesses of natural philosophy by new idealistic fallacies, proves better than anything else that this philosophical trend has outlived itself and is now, very much in the manner of a scorpion, stinging itself to death with its own venom.