popper's third world

Popper's Third WorldAuthor(s): Brian CarrSource: The Philosophical Quarterly, Vol. 27, No. 108 (Jul., 1977), pp. 214-226Published by: Wiley for The Philosophical QuarterlyStable URL: http://www.jstor.org/stable/2218780 .

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214

POPPER'S THIRD WORLD

BY BRIAN CARR

1. INTRODUCTION: OBJECTIVE KNOWLEDGE In the late sixties Sir Karl Popper delivered two papers expounding a

pluralistic metaphysics, "Epistemology Without a Knowing Subject" and "On the Theory of the Objective Mind". These papers were published again in 1972, together with others on closely related matters, in the book Objective Knowledge: An Evolutionary Approach. It is fair to describe the metaphysics which these works expound as a quite new development in Popper's philosophy, and yet the germs of such a theory have really been present in his thought for many years. This paper is an attempt to under- stand the relationship between Popper's earlier work on the methodology of science and this later development, indeed to see how the pluralistic metaphysics is a development of earlier thoughts on the philosophy of discovery. Furthermore, once I have identified the relationship I shall suggest that the new departure is in fact an unnecessary one, for a fallibilistic epistemology can be happily accepted by those who divide up the world more parsimoniously. A fallibilist, I shall suggest, can well be a subjectivist.

Popper's new pluralistic metaphysics contains of course the fallibilistic epistemology within it, for it is concerned precisely with the ontological status of knowledge (particularly scientific knowledge) as described by Pop- per's better-known critical fallibilism. As the glue which binds together the metaphysics and epistemology is the question at issue, it is as well to begin with a sketch of the complete whole. Popper writes as follows:

Without taking the words 'world' or 'universe' too seriously, we may distinguish the following three worlds or universes: first, the world of physical objects or of physical states; secondly, the world of states of consciousness, or of mental states, or perhaps of behavioural dis- positions to act; and thirdly, the world of objective contents of thought (OK 106).1

The fundamental distinction that Popper has in mind in this pluralism is that between the content of thought (or objective content) and the mental (subjective) process which is its vehicle. Popper recognizes certain common ground between his pluralism and Plato's theory of Forms, Bolzano's theory of a universe of propositions and truths in themselves, and Frege's treatment of propositions: to bring out these parallels he at one place describes his third world as ". .. the world of intelligibles, or of ideas in the objective sense; it is the world of possible objects of thought" (OK 154).

1The following abbreviations for works by Popper are used in the text: LSD for Logic of Scientific Discovery, OS for Open Society and its Enemies, C & R for Conjectures and Refutations, OK for Objective Knowledge. See references at end of text.



POPPER S THIRD WORLD 215

The inmates of the third world, so far simply described as the "objective contents of thought", are most importantly the units of knowledge as described in Popper's critical fallibilism. One of Popper's fullest lists goes as follows:

Among the inmates of my "third world" are . . . theoretical systems; but inmates just as important are problems and problem situations. And . . . the most important inmates of this world are critical arguments, and what may be called-in analogy to a physical state or to a state of consciousness-the state of a discussion or the state of a critical argument; and, of course, the contents of journals, books, and libraries (OK 107).

In direct contrast to these third world inhabitants, the inmates of the second world (the world of mental states) include the units of knowledge as described in the traditional epistemology of Descartes, Locke, Berkeley, Hume, Kant and Russell, where knowledge is regarded as a special kind of belief (OK 107). Popper distinguishes "subjective" and "objective" knowledge like this:

(1) knowledge or thought in the subjective sense, consisting of a state of mind or of consciousness or a disposition to behave or to react, and (2) knowledge or thought in an objective sense, consisting of problems, theories, and arguments as such. Knowledge in this objective sense is totally independent of anybody's claim to know; it is also independent of anybody's belief, or disposition to assent, or to assert, or to act. Knowledge in the objective sense is knowledge without a knower: it is knowledge without a knowing subject (OK 108-9).

It can be clearly seen from this that Popper's theory of the objectivity of scientific knowledge is directed at the very same subjectivist target as was the critical fallibilism which came before the metaphysics: metaphysics and epistemology are working in harmony.

Continuing a little further with the outline of the metaphysics, the objectivity of scientific knowledge (or its existence independently of any subject) is illustrated by a book of logarithms produced and printed by a computer (OK 115). The book may be stored in libraries and never consulted as long as men live, and yet it contains objective knowledge. The objectivity of knowledge is even better illustrated in terms of what Popper calls the autonomy of the third world. He writes, for example, that

.the natural numbers are the work of men, the product of human language and of human thought. Yet there is an infinity of such numbers, more than will ever be pronounced by men, or used by computers. . . . But what is even more interesting, unexpected new problems arise as an unintended by-product of the sequence of natural numbers; for instance the unsolved problems of the theory of prime numbers (Goldbach's conjecture, say). These problems are clearly autonomous. They are in no sense made by us; rather, they are dis- covered by us; and in this sense they exist, undiscovered, before their discovery (OK 161).

As this quotation also indicates, the autonomous third world is to be con- strued as man-made, as a human product comparable to the non-living



216 BRIAN CARR

structures which other animals produce: "such as spiders' webs, or nests built by wasps or ants, the burrows of badgers, dams constructed by beavers, or paths made by animals in forests" (OK 121; cf. 159). Like these other objective structures, the third world is described as an unintended by- product of actions which were directed at other aims (OK 117), in particular the third world being a by-product of human language. What Popper calls "the higher functions of human language . . . the descriptive function and the argumentative function" (OK 119) are held responsible for the origin of critical argument and knowledge in the objective sense, for with these functions of language come the regulative ideas of truth content, and veri- similitude (OK 120).

Finally, to complete this sketch, Popper stresses the feed-back effect from the third world upon the second, for a theory produced will bring with it new unexpected problems which in their turn will stimulate the fresh production of tentative solutions or tentative theories-a process of course described in Popper's fallibilist epistemology as a form of Darwinian evolution (OK 119, 161). This dynamic conception of the third world sometimes appears-unintentionally, I have no doubt-to be replaced by a static one, where the third world is conceived of as full for all time with all possible products of thought: when he writes, for example, that

. . . there are many theories in themselves and arguments in themselves and problem situations in themselves which have never been produced or understood and may never be produced or understood by men (OK 116)

and when he describes the man-made third world as . . . superhuman in that its contents are virtual rather than actual objects of thought, and in the sense that only a finite number of the infinity of virtual objects can ever become actual objects of thought (OK 159).

2. Two KINDS OF OBJECTIVITY I hope to have indicated that there is a close union between Popper's

fallibilist epistemology and pluralistic metaphysics, in fact that the metaphysics can be seen as a way of presenting the epistemology. With the intention of throwing further light on the precise form that this union takes, I want to introduce now a distinction between two things that might be understood by the "objectivity of science", separable notions of objectivity which are conflated by the metaphysics of three worlds.

The difference between the two notions in question can be put like this: to talk of the "objectivity of scientific knowledge" in one sense is to talk of the fact that such knowledge is in some way independent of any particular individual, that it transcends the whim of the individual; to talk of the "objectivity of scientific knowledge" in another sense is to talk of the (supposed) fact that such knowledge is in some way independent of all indi- viduals, that it has a reality outside of the minds of the knowers. I will try




to fill out this distinction sufficiently to exhibit the difference in question. (a) To begin with the former idea of scientific objectivity, this is the

conception (important, widely recognized, but difficult to describe) of the essential rationality or intersubjectivity of scientific theories and hypotheses. Compared with scientific systems, rightly or wrongly, metaphysical systems or religious beliefs or moral codes might look like simple personal conviction, unarguable prejudice. The supposition that science is objective in this sense was thought, for example, by Imre Lakatos to have been undermined by Kuhn's paradigm description of scientific revolutions, a description leading to scientific irrationality and relativism. Lakatos wrote for instance:

For Kuhn scientific change-from one "paradigm" to another-is a mystical conversion which is not and cannot be governed by rules of reason and which falls totally within the realms of the (social) psycho- logy of discovery. Scientific change is a kind of religious change (Criticism and the Growth of Knowledge, p. 93).

Kuhn was of course quick to rebut any suggestion of an attempt to under- mine the objectivity of science (op. cit., p. 261), and rightly so, for however we ultimately describe scientific objectivity, that science transcends the individual whim is a datum from which philosophy must start.

(b) It is certainly not my intention to deny that Popper uses the term 'scientific objectivity' in the sense so far illustrated; far from it. He wTites in the Logic of Scientific Discovery (p. 44):

My use of the terms 'objective' and 'subjective' is not unlike Kant's. He uses the word 'objective' to indicate that scientific knowledge should be justifiable, independently of anybody's whim; a justification is "objective" if in principle it can be tested and understood by anybody.

(At the same place he writes "The words 'objective' and 'subjective' are philosophical terms heavily burdened with a heritage of contradictory usages and of inconclusive and interminable discussion"!) What I want at the moment to point out is that Popper also uses the expression 'objectivity of science' to refer to the supposed independent existence of the content of thought from the subjective thought-vehicle. This is Popper's realism with respect to the third world of objective knowledge, and it is this notion of objectivity which comes to the forefront when Popper is presenting his metaphysics as a corrective to the traditional "subjectivist" construction of knowledge. The anti-subjectivist construction removes any element of belief or behavioural disposition and treats simply of the problems, theories, and arguments as such. The anti-subjectivist "objectivity" is clearly different from the intersubjective, rational, objectivity sketched above.

I said above that the metaphysics of three worlds conflates these two notions of objectivity, and this can be seen from Popper's description of the feed-back effect of the third world on the second. He writes:

With the development of a descriptive language . . . a linguistic third world can emerge; and it is only in this way, and only in this



218 BRIAN CARR

third world, that the problems and standards of rational criticism can develop. ... It is to this development of the higher functions of language that we owe our humanity, our reason (OK 120-1).

We are here presented with an explicit connection between the existence of a linguistic third world of objective knowledge and the idea of standards of rational criticism, that is, of the objectivity of scientific knowledge: the descriptive function of language is a condition without which the third world could not have emerged, and so also the problems and standards of rational criticism. In the same way, Popper connects the argumentative function of language, again a condition for the emergence of the third world, with the rationality of science:

Its evolution has been closely connected with that of an argumentative, critical, and rational attitude. . . . Like the descriptive use of language, the argumentative use has led to the evolution of ideal standards of control, or of "regulative ideas" (using a Kantian term): the main regulative idea of the descriptive use of language is truth . . . and that of the argumentative use of language, in critical discussion, is validity (OK 237).

It is interesting to note that Popper forged a link between the idea of rational objectivity and his opposition to "belief philosophy" prior to the explicit development of his three worlds metaphysics, in his treatment of what he calls the "objective and absolute" concept of truth. In ch. 10 of Conjectures and Refutations, the idea of truth as correspondence with the facts (rehabilitated by Tarski's semantic theory-see also, e.g., OK 46) is claimed to have an important role to play in the theory of scientific progress even though this may indeed be only as a regulative principle; a subjectivist theory of knowledge is however precluded from using such a notion. Rivals to the Tarskian objective theory are described as subjective or "epistemic" in that

. . .they all stem from the fundamental subjectivist position which can conceive of knowledge only as a special kind of mental state, or as a disposition, or as a special kind of belief (C & R 225).

The subjectivist, it seems, is faced with the problem of finding a way of distinguishing those beliefs which are well-founded and so constitute knowledge, that is, of finding a criterion or "symptom by which to differentiate the experience of a well-founded belief from other experiences of belief" (C & R 225). It is the peculiar mark of the subjective or epistemic theories of truth that they aim at such a criterion. Of course, the correspondence theory of truth is then of little use to the subjectivist, for it could not serve his purpose. To what extent this is a fair assessment of the limitations of a subjectivist epistemology is something that I shall now take up.

3. OBJECTIVITY, INDUCTION, AND BELIEF

Popper's critical fallibilism is indeed his solution to the problem of the (rational) objectivity of science, so a brief consideration of this epistemology will provide part of the picture we are seeking. Now an integral part of the



POPPER S THIRD WORLD219

notion of objectivity is the intersubjective, social character of knowledge, and this is of course a feature which Popper has taken pains to stress. In The Open Society (Vol. 2, 216-220) he takes to task what he calls "the sociology of knowledge" for seeing objectivity as resting on the individual scientist's impartiality: rather scientific objectivity is a product of the social or public character of scientific method:

Objectivity is closely bound up with the social aspect of scientific method, with the fact that science and scientific objectivity do not (and cannot) result from the attempts of an individual scientist to be "objective", but from the co-operation of many scientists. Scientific objectivity can be described as the intersubjectivity of scientific method (OS 2, 217).

He goes on to describe this intersubjectivity as resting on the existence of free criticism, on the one hand, and the public character of the experiences (observations, tests) to which scientific theories must be answerable. This account is in agreement with the epistemology developed in his earlier Logic of Scientific Discovery, where the objectivity of scientific statements is said to lie in the fact that they can be intersubjectively tested (LSD 44). Such a characterization immediately has implications for the content of science and its foundations. It implies, for example, that scientific statements are uni- versal in form. It implies further that the statements reporting results of observation, and so tests of other scientific statements, are basic scientific statements only in a relative sense:

If we adhere to our demand that scientific statements must be objective, then those statements which belong to the empirical basis of science must also be objective, i.e., intersubjectively testable. Yet intersubjective testability always implies that, from the statements which are to be tested, other testable statements can be deduced. Thus if the basic statements in their turn are to be intersubjectively testable, there can be no ultimate statements in science (LSD 47).

Furthermore, it implies that the positivist's attempt to rest scientific knowledge upon the firm foundation of "protocol sentences" is fundamentally misguided-for the protocol sentences (records of immediate observation) of Carnap and Neurath are low on the scale of intersubjective testability (C & R 267).

This conception of the objectivity of science has proved a philosophically fruitful one, and Popper has developed and refined its features over the years. The development of science is described as a Darwinian trial-and- error process, whereby conjectures are submitted to the test of experience in the form of attempts at refutation, and so far unrefuted conjectures are never regarded as removed from the sphere of potential falsification-they remain forever hypotheses or conjectures. With respect to some of the develop- ments it is somewhat questionable whether the spirit of the original account is retained: for example, in ch. 10 of Conjectures and Refutations it is suggested that a certain kind of change, growth in the sense of increased potential truth content of theories, is an essential requirement of the rational and



220 BRIAN CARR

empirical character of scientific knowledge; such a criterion seems incongruous if the original simpler criterion of falsifiability simpliciter is also retained (C & R 249). (This of course has given some scope for the suggestion, by Lakatos, of levels of sophistication in Popper's epistemology.2) Again it is questionable (and has been questioned, for example, by Wesley Salmon3) whether the introduction of the criterion of corroboration for the choice (for theoretical and practical purposes) of one among the unrefuted theories is consonant with the spirit of critical fallibilism. A development of note has been the widening of the original idea of scientific objectivity as falsifiability to a conception of objectivity or rationality generally as criticizability (or "rational control by critical discussion"-LSD 44): metaphysical positions are certainly not falsifiable in the original sense of confrontation with experience, but metaphysics is not on those grounds precluded (C & R ch. 8).

A feature of this critical fallibilism which it is essential for our purposes to note is that it is explicitly developed in contrast with another account of the objectivity of scientific knowledge-that of inductivism, which views the results of scientific enquiry as firmly raised on the foundations of observations. Popper's criticisms of this account of science are well known. On the one hand, they concern the very idea that one can start from observations without the background of a set of hypotheses, expectations as to what one will find, and stress moreover the illegitimacy (or rather the absence of any proof of the legitimacy) of arguing ampliatively from premises to a con- clusion which goes beyond them. On the other, they concern the suggestion of certain knowledge or established theories in the realm of experience. Ob- servation, the "ground level" where one might expect to find certainty if anywhere, is shown to be far from the simple absorbing of information that the "bucket theory of the mind" would have us believe: observation is always in terms of some theory, from a point of view, "theory-laden".

This so far is part of the connection between the (rational) objectivity of scientific knowledge and Popper's thesis of its (realist) objectivity. The epistemology, to repeat, is Popper's account of the intersubjectivity of science. The description Popper gives of his third world incorporates this epistemology. What provides the final link between the epistemology and the metaphysics is Popper's belief that a subjectivist approach to knowledge, one which sees knowledge as a special state of mind of the knower, is committed also to the equation of knowledge with certainty. Critical fallibilism is opposed to the search for certainty, and such a search is seen as an essential part of the subjectivist approach. With this connection in mind, Popper's realism with respect to the third world of objective knowledge is seen as the reaffirmation of the fallibility of human knowledge.

That Popper connects subjectivism with the search for certainty is evident from a number of his writings. For example, in Objective Knowledge

2See the paper by Lakatos in Criticism and the Growth of Knowledge. 3Salmon, Foundations of Scientific Inference, 26.




the "main weakness" of the "commonsense theory of knowledge" is said to lie in its characteristic claim that

In order that a kind of belief, or a state of mind, should amount to more than "mere" belief, and should be capable of sustaining the claim that it amounts to an item of knowledge, we require that the believer should be in possession of sufficient reasons for establishing that the item of knowledge is true with certainty (OK 75).

For this reason the subjectivist is held to have failed in giving an account of scientific knowledge:

The whole vast and important field of theories which we may describe as "scientific knowledge" would, owing to its conjectural character, not qualify as knowledge at all. For according to the commonsense theory of knowledge, knowledge is qualified belief-belief so qualified that it is certainly true. And it is precisely this kind of qualification which is missing in the vast and important field of conjectural knowledge (OK 75-6).

Of course, if there is to be a criterion for a belief's being certainly and un- failingly true, and so knowledge, such a criterion will need to be some apparent feature of the immediate situation. About this possibility Popper is suitably scathing:

The difficulty is great, for how can we distinguish within the realm of belief? What are the criteria by which we can recognize truth, or a sufficient condition? Either by the strength of the belief (Hume), which is hardly rationally defensible, or by its clearness and distinct- ness, which is defended (by Descartes) as an indication of its divine origin; or, more straightforwardly, by its origin or its genesis, that is to say by the "sources" of knowledge. In this way, the commonsense theory is led to the acceptance of some criterion of the "given"

. .knowledge; to the sense-given datum; or to a feeling of immediacy, or directness, or intuitiveness (OK 77).

Again, Popper's equation of subjectivism and certainty can be seen in his (already mentioned) treatment of the correspondence theory of truth. Such a theory is, he says, "objectivist" in regarding truth as a property of theories rather than of an experience or belief:

The three rivals of the correspondence theory of truth-the coherence theory which mistakes consistency for truth, the evidence theory which mistakes 'known to be true' for 'true', and the pragmatic or instrumentalist theory which mistakes usefulness for truth-these are all subjectivist (or "epistemic") theories of truth, in contradistinction to Tarski's objective (or "metalogical") theory. They are subjective in the sense that they all stem from the fundamental subjectivist position which can conceive of knowledge only as a special kind of mental state, or as a disposition, or as a special kind of belief (C & R 225).

That Popper equates the "second world approach" to knowledge with the search for certainty in the sense explained is, I think, beyond question. It does provide, what is more, the link between his fallibilist epistemology and his third world reaIism: in rejecting the idea of certainty in empirical knowledge Popper is led by this connection to reject also any account of knowledge which equates it with belief.



222 BRIAN CARR

4. A SUBJECTIVIST FALLIBILISM? I want to suggest the possibility of combining subjectivism with some

form of fallibilism. I will not present in detail a version of subjectivist fallibilism, but will indicate in outline what I think is a defensible idea of scientific knowledge: true belief grounded in a manner which accords with shared criteria.

The kind of fallibilism that I have in mind differs crucially from Popper's doctrine, but I will begin with points of agreement. Essential to both versions is the rejection of the idea of an infallible guide to the truth, a criterion of truth in that strict sense. This element of traditional epistemology is in no way defensible. Firstly there is the complete failure to provide anything that even looks like an adequate candidate for such a criterion: Descartes' "clear and distinct idea" criterion suffers from the ever-present danger that one might only think that one clearly and distinctly perceives; the empiricists' alternative of seeking the criterion in the source of the idea depends on the mistaken supposition of unadulterated data of sense. There would moreover appear to be a logical objection to criteria in this sense, in that if the criterion is logically conclusive as to the truth, then the truth must be logically reducible to the criterion itself, and this view leads directly to a verificationist account of meaning. (Presumably Descartes' "criterion" would escape this objection in that the connection between the criterion and the truth is supported by God instead of logic.) These and arguments familiar from Popper's writings suffice to preclude the use of this notion of a criterion. A subjectivist fallibilism is not however precluded from using any notion of a criterion as long as the criterion's being satisfied leaves open the possibility that that which it supports is false. This of course is not an unfamiliar situation, for in the ordinary application of everyday concepts the application goes through on "inconclusive" criteria: the way in which we recognize horses, for example, leaves open the possibility of a clockwork mechanism inside a synthetic hide, but we know horses when we meet them nevertheless. The point is that when the criteria are satisfied we are in a position to claim knowledge and there is an obvious sense in which the question of the truth of our claim is a separate issue (just as there is an obvious sense in which it is not).

It is on the question of our understanding of truth that the next point of agreement between our fallibilisms is to be found. As my earlier quota- tions indicate, Popper takes the correspondence theory to be acceptable only on an objectivist approach to knowledge, and this for the reason that subjectivists are committed to criteria in the rejected sense. A pragmatic or coherence theory is perhaps attractive, though by no means necessary for a traditional epistemology that incorporates such criteria, but in as much as the suggested subjectivism also rejects criteria it is possible for it to counten- ance a correspondence theory.

Most importantly our fallibilisms concur in opposing the idea that know-




ledge involves (absolute) certainty. To reject the notion of an infallible criterion of truth is not in itself the same as rejecting that of certainty, for were there no one unfailing mark of truth there might yet be candidates for certain knowledge. Our fallibilisms reject this latter possibility. Trad- itional epistemology was committed to seeking such candidates, and we have been offered supposedly indubitable truths by Descartes and incorrigible propositions by empiricists. Descartes' examples (in the First Meditation) make it abundantly clear that the fault (in his eyes) of ordinary knowledge claims was that they rested on logically inconclusive grounds, grounds that left open a host of possibilities such as interference by an evil demon. Certainty was achieved only when that gap was closed. Similarly, the incorrigible proposition can be known, for on the evidence it is certainly true, it goes nowhere beyond the facts which are directly apparent. A "belief on shared criteria" account can dispense with this notion of certainty by distinguishing it from an alternative notion of "certainty beyond all reasonable doubt". This latter pertains to the circumstance where the grounds for a proposition are conclusive simply in that the relevant criteria are fully satisfied.

So far our two fallibilisms are essentially in agreement: the difference lies in our accounts of the objectivity (intersubjectivity) of science, Popper's fallibilism incorporating as an essential element the thesis that the objectivity of science is to be understood in terms of the falsifiable character of scientific statements. The subjectivist fallibilism which I am sketching would locate the objectivity of science in a rather different place. Popper (as we have seen) stresses the intersubjective, social character of science and locates this in the fact that scientific statements can be intersubjectively tested. His fallibilism replaces the traditional inductivist account of scientific objectivity in terms of the certainty with which scientific results are pur- portedly established. In following Popper's rejection of certainty, subjectivist fallibilism must present an alternative account of objectivity, and this it does by pointing to the fact that beliefs are held on grounds which it is publicly recognized warrant such beliefs. Belief is grounded in a manner which accords with shared criteria, and it is the existence of these shared criteria that allows a distinction to be drawn between how things seem to be and how they are, between the expression of mere opinion and the state- ment of fact. If and only if the conditions laid down by those criteria are satisfied, one is warranted in believing that such-and-such are the facts. This is where the intersubjective character of science lies and why we talk of its "objectivity". Popper's account of objectivity does not support the distinction between opinion and fact; moreover, on this alternative account we have an explanation why Popper is correct in seeing the statements of science as intersubjectively testable, namely that they are grounded in accordance with public shared criteria.

I have tried to sketch an account of the objectivity of science which,



224 BRIAN CARR

while not departing from the traditional equation of knowledge with a form of belief, nevertheless does not suppose it possible to attain the sort of certainty that traditional epistemologists have sought. It is of course true that epistemology has traditionally been both subjectivist and committed to certainty in the questionable sense: there is, however, no logical connection between an analysis of knowledge in terms of belief and an account of the objectivity of science in terms of the certainty of its results. Belief need not be, nor in general is it, unyielding conviction. Indeed, though the subjectivist fallibilism which I have sketched takes the objectivity of science to lie in the shared criteria on which beliefs are based, there is no logical objection to a subjectivism which accepts even more fully Popper's own fallibilism. Such a subjectivist would take objectivity to rest, not in the way beliefs are supported, but in a readiness to revise one's beliefs in the face of adverse criticism. This shows most clearly how the connection between Popper's critical fallibilism and World Three realism may be severed.

A subjectivist who accepted Popper's fallibilism would also be immune from the criticisms Popper has made of an inductivist view of knowledge. The fallibilism which I have pointed to is an inductive one, and would have to present a defence on that score. It would have in this connection some strong points in its favour, for it does not need to include some of the major traditional elements which justly attract Popper's criticism: for one thing, it rejects the notion of the firm establishment of empirical knowledge; for another, it does not assume that criteria of belief present a set of canons for the discovery of the laws of nature. It is inductive only in the sense that it sees belief as warranted in circumstances where the grounds are obviously logically inconclusive, for even when the criteria are fully satisfied there is a logical gap from there to the belief.

5. CONCLUDING REMARKS I have limited myself to giving only the briefest outline of a subjectivist

fallibilism, for my concern has been with the possibility of some such account. If pressed, however, to expand on that outline, I think it would be important for a fallibilist of this type to add that, although talk of "belief on shared criteria" may give the opposite impression, belief is not an all-or-nothing affair. The certainty that a believer has in the truth of his belief obviously varies widely. A rational man will apportion his degree of conviction on the basis of what certainty is warranted in his circumstances by the criteria of belief. The shared criteria, in other words, do not serve simply to decide when a belief is warranted and when it is not, but rather to decide what grade of belief is warranted in the circumstances.

What should be added also to the fallibilism as sketched above is some indication of what the shared criteria are that provide for the objectivity of science. So far nothing has been said to distinguish scientific objectivity from the objectivity of other disciplines such as philosophy, theology or




aesthetic criticism, in all of which one may talk of judgements on shared criteria. This, I think, is how it should be: an account of objectivity in general quite logically precedes an account of how such objectivity is achieved in different disciplines. To arrive at scientific objectivity, something has to be said about the nature of the shared criteria that produced science. Such an account might begin from the point that the aim of science is to explain and control our environment, with the consequence that the stress in the criteria of belief is on such factors as internal and contextual simplicity, predictive power, and empirical support.

I will conclude, for the purpose of stating my position as clearly as possible, by commenting on a possible charge levelled against the suggested subjectivist fallibilism. This is the objection that such a theory gains what- ever plausibility it has by simply ignoring what Popper calls "knowledge" and describing what he has already admitted to exist, the second world subjective states of the scientist. Popper's "knowledge" simply does not comprise beliefs; it comprises puzzles, problems, theories, hypotheses. An account of knowledge as belief on shared criteria is, therefore, an account of something else.

Now such an objection obviously misses the mark. To begin with, Popper and I are not talking about different things, but have an identical subject-matter, the discipline of science. We are of course offering different analyses. Popper's metaphysics makes room for beliefs in the sense of mental particulars and hence gives an appearance of tolerance which may mislead, and thus suggest the present objection.

Secondly, the proffered fallibilism does not at all deny that there are in science the things that Popper says there are. There are hypotheses, theories, problems, states of an argument. The subjectivist theory has in fact not committed itself against these things and there is no reason why it should do so. It would be consonant with such a theory to say that there are hypotheses which are hypothesized by people, theories which are theorized, problems which are had by people, just as there are beliefs which are believed by people. Indeed, it is difficult to see how there could be beliefs if there were not such things.

Finally, the objection would most obviously be seen to fail if, to my thesis that a subjective fallibilism is possible, arguments were added showing that a subjectivism is necessary-for then Popper's thesis of an independent third world would be clearly incoherent. Such a line of argument looks a plausible one. There is a distinction (as Frege said) between thoughts and thought contents-the latter stand in logical relations to one another, the former in psychological-but the latter are contents of thought and so cannot be understood independently of it. In similar fashion one can distinguish between the "subjective" conviction of the believer and the logical dimension of the belief complex, the proposition in its relation to considerations brought forward in its favour, but abstracting in that way from the second world



226 BRIAN CARR

should not lead us to postulate an independent third world. So are problems, hypotheses, theories-libraries even-the things they are only for people. Popper's third world metaphysics is a further example (along with well- known accounts of notions such as explanation and prediction) of putting up the logical aspects of essentially subject-referring notions as the whole of the matter.

University of Exeter

REFERENCES

Lakatos, I. (ed.): The Problem of Inductive Logic (Amsterdam, 1968). Lakatos, I. & Musgrave, A. (edd.): Criticism and the Growth of Knowledge (Cambridge,

1970). Popper, K. R.: The Logic of Scientific Discovery (London, 1934, 1959). Popper, K. R.: The Open Society and its Enemies (London, 1945, 1962). Popper, K. R.: Conjectures and Refutations (London, 1963, 1969). Popper, K. R.: Objective Knowledge: An Evolutionary Approach (Oxford, 1972). Salmon, W. C.: The Foundations of Scientific Inference (Pittsburgh, 1966).



popper's third world

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