Verificationist Anti-realism

Going for idealism is not the only way to go for a kind of mind-dependence of the world. The other way is weaker; it does not centre on the irreducibility condition— since it is perfectly OK with it—but on the objectivity condition.

There is a long anti-realist philosophical tradition according to which it does not make sense to assert the existence (or reality) of some entities unless this assertion is understood to be connected to..., where the ellipsis is filled with the requirement of fulfilment of a suitable epistemic/conceptual condition. Putnam's (in his middle period) favourite filling would be based on the condition of rational acceptability; Dummett's would relate to warranted assertibility; and Kant's own line was related to the possibility of something being encountered in experience.

In the sequel I will deal mostly with Dummett and his disciples. But a quick note on Kant is worthwhile.

3.1 A Note on Kant on Scientific Realism

Kant's Transcendental Idealism is captured by his dictum: “everything intuited in space or in time, hence all objects of an experience possible for us, are nothing but appearances, i.e., mere representations, which, as they are represented, as extended beings or series of alterations, have outside our thoughts no existence grounded in itself.” Opposing this view, Transcendental Realism “makes these modifications of our sensibility into things subsisting in themselves, and hence makes mere repre­sentations into things in themselves” (Critique A 490-1; B 518-9).^[70] Kant's con­ception of representation is quite technical. It does imply that the represented—qua represented in space and time or as falling under the schematised categories of pure understanding—is in an important sense mind-dependent.

Hence, critical or formal idealism, as Kant called his position, is not a reductive position; it does not concern whether material things exist and whether they are reducible to mental entities. It concerns the conditions under which it is proper to say that objects exist—and these conditions include the properties that have to be pred­icated of them by virtue of which objects can be known (cf. Kant 2004, §§289-91).

Kant, notably, had no problem at all in accepting the existence of invisible entities posited by the best theories of his time.^[71] In fact, they are no less part of appearances than macroscopic entities since they are in space. And they are no less real than them. Would it be then a foregone conclusion that Kant was a scientific realist?

The answer is complicated by the fact that Kant famously allowed the existence of noumena—of things as they are in themselves. This, to be sure, is a limiting concept, but it does allow for an in-principle divergence between how things appear to be and how they are in themselves. (This, in fact, was a main criticism that Hegel levelled against Kant.) But in many ways, the Kantian noumena are an idle wheel in his philosophy of nature (cf.

What is, in principle, knowable of the world cannot possibly, for Kant, be different from what is licensed as knowable by the categories of pure understanding and the a priori forms of pure intuition. The famous Copernican turn suggests as much:

Up to now it has been assumed that all our cognition must conform to the objects; but all attempts to find out something about them a priori through concepts that would extend our cognition have, on this presupposition, come to nothing. Hence let us once try whether we do not get farther with the problems of metaphysics by assuming that the objects must conform to our cognition, which would agree better with the requested possibility of an a priori cognition of them, which is to establish something about objects before they are given to us (Bxvi).

But since there can in principle be more content in the world than what is in principle knowable by sensible intuition (the noumena as opposed to the phe­nomena), Kant seems to honour not just the irreducibility condition but something akin to the objectivity condition. Still, the verdict is not straightforward. For the phenomena—which for Kant include everything that exists and is in principle knowable—are mind-dependent in a way that compromises their objective exis­tence (in the sense noted in the Introduction). The reason for this is that the exis­tence of the phenomena is connected with the obtaining of certain epistemic conditions which render them knowable (including thinking of them as being in space and time). Kant was quite upfront regarding the implications of this commitment:

Thus the transcendental idealist is an empirical realist, and grants to matter, as appearance, a reality which need not be inferred, but is immediately perceived.

If the whole corporeal world depends on the thinking subject in the sense that is a network of appearances (in the technical Kantian sense which allows their reality and their conformity to synthetic a priori principles of knowledge), Kant's empirical realism can hardly honour the spirit of the objectivity condition.

3.2 Dummett’s Semantic Anti-realism

Michael Dummett famously resuscitated verificationism by tying truth to justifi­cation or warranted assertibility. As he (Dummett 1982, 108) put it, a “statement cannot be true unless we know it to be true, at least indirectly, or unless we have means to arrive at such knowledge, or at least, unless there exists that which, if we were aware of it, would yield such knowledge”. For Dummett a view of reality is not merely a view of what kinds of objects there are and of “what constitutes the existence of such objects”. As he says, “it is necessary to say what kinds of fact obtain, and what constitutes their holding good” (Dummett 2006, 2-3). But talk of facts brings with it talk of truth, since the facts are the true propositions. Hence, for Dummett, the concept of truth plays a central—and ineliminable—role in the realism debate.

In this setting, to resist realism is to resist the realist view that what makes a statement true is an independently given reality which renders our statements true when they are true and false when they are false; that is a reality which is “inde­pendent of our knowledge of it and of our means of attaining such knowledge” (Dummett 2006, 65). This kind of anti-realism fosters a notion of truth which is not evidence-transcendent; hence it denies the principle of bivalence. More specifically, it ties ascriptions of truth with the existence of an effective decision procedure which allows deciding whether a statement in a given domain is true or false. Famously, Dummett's model of anti-realism is intuitionism in mathematics.

The point relevant to our purposes is that this decision procedure is not con­nected to a certain type (or types) of object(s). Material objects and facts about them, insofar as statements about them are decidable by means of perception or other observational procedures, are parts of reality. Hence, the existence of a fact of the matter about statement S (e.g., that material objects exist or are real) depends on the existence of grounds for holding that there is a fact of the matter about the outcome of a decision procedure such that were it to be carried out, or had it been carried out, the truth of S would be, or would have been, decided. The subjunctive or counterfactual element in the foregoing clause is significant. The decision pro­cedure need not be actually carried out; it is enough that it can, or could, be carried out. Those (and only those) statements for which the relevant decision procedure is available, that is those statements which are decidable, are such that the principle of bivalence holds. Where there is no possibility of knowing (where, that is, there is no relevant decision procedure) there are gaps. Dummett's anti-realism, then, consists in the claim that there can be gaps in reality, that is that reality is

in some degree indeterminate, for we have no conception of reality save as that which renders true those true statements we can frame and those true thoughts we can entertain.

The presence of gaps in reality (associated with verification-transcendent assertions) does not imply that if the truth of an assertion is verified, a gap in reality is filled with a fact popping into existence. Rather, Dummett's point is that if it is at all possible to verify a truth, then a gap in reality would not have been there in the first place. Note that this view is consistent with the claim that the facts that there are would have existed even if human beings had not evolved relevant to their recognition epistemic capacities. What, of course, could not have possibly existed for Dummett are facts for recognition-transcendent truths. To put the point differ­ently, Dummett's anti-realism does not imply that the determinate part of reality (which is the whole of reality for Dummett's anti-realism) wouldn't be there if beings like us had not evolved relevant epistemic capacities to recognise truth.

But some extra care is needed here. Dummett insists that something can be a fact only if it can be known to be a fact, which is the same thing as saying that there is a fact of the matter about the truth of a statement S only if this truth can be in principle verified. As he (Dummett 2006, 92) put it:

On a justificationist view, however, what we could have known extends only so far as the effective means we had to find out: the entailment is not from its being true to the possibility of knowing it, but in the opposite direction. It would be wrong to say that we construct the world, since we have no control over what we find it to be like; but the world is, so to speak, formed from our exploration of it.

This is a striking point. Obviously, it places significant constraints of what there is in the world. As Dummett put it: “Our world is thus constituted by what we know of it or could have known of it” (Dummett 2006, 92). There is no more content in the world than what can be in principle known of it. And it is there, (constituting the world), in some important sense, only insofar as it can be known to be there. It can be seen then that though Dummett honours the irreducible existence condition, he does not accept the objective existence condition.

To probe this point a bit more, let us note that when it comes to the philosophy of science, Dummett is an anti-instrumentalist. But he goes beyond this by taking for granted a lot that is posited by current science. Though he stresses that some of the theoretical entities of science (“black holes, quarks, hidden dimensions, anti-matter, superstrings”) “seem bizarre”, he takes it that “it is difficult to make a sharp demarcation between constituents of the everyday world and those of the physicist’s world. Electric currents were not but now are part of the everydayworld; presumably radio waves must also be assigned to it” (Dummett 1991, 5). But here again, insofar as he advocates some form of realism about theoretical entities it is because and insofar as statements about them are recognisable as true. Dummett admits that “we cannot but view science, at least before it transcends some critical level of abstraction, as attempting to arrive at such descriptions [of an object as it is in itself]”, (Dummett 1996, 410) but this is because and to the extent in which scientific statements are verifiable in roughly the same way as statements about common-sense objects.

Insofar as the resulting position is a kind of scientific realism, it has accepted the basic tenet of Dummett’s anti-realism! The independence of the world has been compromised not by denying that theoretical entities are real and irreducible but by denying that truths about them are evidence-transcendent. Hence, theoretical enti­ties are indeed real, but only insofar as truths about them can be known and precisely because (in some sense of because) they can be known.

As is well known, the middle Putnam came to accept Dummett’s verificationism. Recounting this ‘conversion’, Putnam noted that his basic disagreement with Dummettian neo-verificationism was about leaving the possibility open of a gap between justification-by-present-evidence and truth: he took it that truth should be identified with “idealised justification” (Putnam 1983, xvii). Part of his thought was that even if truth is tied to justification, one should be careful how exactly this tie is effected. As he (Putnam 1983, 162) put it, he was looking for a position “which recognises a difference between ‘p’ and ‘I think that p’, between being right, and merely thinking one is right without locating the objectivity in either transcendental correspondence or mere consensus”. Truth is not a property that can be lost—nor does it have a sell-by date. Hence, the verificationist notion that replaces (or cap­tures) truth should be such that it honours this property of truth. The ‘correctness’ of an assertion is a property that can be lost, especially if it is judged by reference to current standards or consensus (these come and go). Because of this Putnam tied correctness to “the verdict on which inquiry would ultimately settle” (Putnam 1982, 200). This might suggest that Putnam adopted an account of truth that has been associated with Charles Peirce, but as he (Putnam 1990, viii) noted, this (Peircean) ideal-limit-of-inquiry theory truth is “fantastic (or utopian)”.

In the midst of his conversion to verificationism, (or to internal or pragmatic realism, as Putnam tended to call it), he published a piece in which he did endorse scientific realism, suitably dissociated from both materialism and metaphysical realism (cf. Putnam 1982). He took scientific realism to involve commitment to the following theses: theoretical entities have irreducible existence (they exist in the very same sense in which ordinary middle-sized objects exist and are irreducible to either them or complexes of sensations); theoretical terms featuring in distinct theories can and do refer to the same entities (hence, there is referential continuity in theory-change); there is convergence in the scientific image of the world; and scientific statements can be (and are) true. Yet, the verificationist Putnam of the early 1980s took truth to be the “correct assertibility in the language we use” (Putnam 1982, 197). So scientific realism was dressed up in a verificationist gar­ment. But is this scientific realism proper?

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