The Possibility of Divergence

The Dummett-(middle) Putnam verificationism is clearly anti-idealist. It entails (or at least it is consistent with the claim) that material objects are irreducibly real (be they the middle-sized entities of common sense or unobservable entities).

Opposing verificationist anti-realism, the realist claim of mind-independence should be understood as logical or conceptual independence: what the world is like does not logically or conceptually depend on the epistemic means and conceptualizations used to get to know it. But can we understand this kind of independence more precisely?

I think the best way is by endorsing the possibility of a divergence between what there is in the world and what is issued as existing by a suitable set of cognitive and epistemic conditions. Verificationist anti-realism a priori precludes this possibility of divergence by advancing an epistemic conception of truth. No matter what the details of this conception are, the key idea is that truth is conceptually linked with epistemic conditions in such a way that it is not possible that a theory is epis- temically right (it meets the relevant epistemic condition e.g., being ideally justified or warrantedly assertible) and false.

It’s then natural to think that honouring the possibility of divergence requires adopting a substantive non-epistemic conception of truth. Do we have to say more about this notion of truth? At this stage, this is not necessary. We might try to offer a theory about the nature of truth, e.g., in terms of correspondence. This would be useful when it comes to understanding truth, yet the main point is that the required notion of truth is non-epistemic, viz., that truth is cognition-independent (cf. Vision 2004, 15). Note that this last claim does not imply that necessarily truth is unknowable; (this very admission would defeat the realists’ epistemic optimism). But it implies that whether or not a truth-maker is knowable is independent of its eligibility as truth-maker. An attraction of this broad way to understand the non-epistemic nature of truth is that the nature of truth-makers is left unspecified in the sense that any sort of thing (be it physical or mental or abstract) can be a truth-maker. As I have argued elsewhere (cf. Psillos 2005), realism in general and scientific realism in particular need not be driven by a fundamentalist conception of reality, where only an elite set of things or facts can be truth-makers. To put the point somewhat crudely, one does not cease to be a scientific realist about, say, psychology if one is not a physicalist, or if physicalism is wrong. Nor is scientific realism about psychology disqualified from the start because psychological entities may well be mental entities.

The key idea behind a non-epistemic account of truth is an asymmetric depen­dence of the theories (and beliefs) on the world. This asymmetry might well be captured (as the early Putnam suggested) by some general theses about what truth is not. One of them is that truth should not be conceptually equated with whatever logically follows from accepted scientific theories, even when these theories are empirically adequate and well-confirmed (cf. 1978, 34-5).

This modal fact, if accepted, has a certain significant implication: there is a way the world is independently of how it is being described by humans—even at the ideal limit of inquiry and when all evidence has rolled in. This is a view that has been associated with the so-called Metaphysical Realism. Many (including famously the middle Putnam) have come to reject it, arguing that it is a mistake to think there is just one (privileged) way the world is; hence that there is just not a single (privileged) way to describe the world. Putnam employed the so-called ‘model-theoretic’ argument against metaphysical realism. But as I have argued in my (2012) (following the lead of others, especially Lewis 1984) this argument offers far from compelling reasons for rejecting Metaphysical Realism.

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