Abstract
Functionalism about truth is the view that truth is an explanatorily significant but multiply-realizable property. According to this view the properties that realize truth vary from domain to domain, but the property of truth is a single, higher-order, domain insensitive property. We argue that this view faces a challenge similar to the one that Jaegwon Kim laid out for the multiple realization thesis. The challenge is that the higher-order property of truth is equivalent to an explanatorily idle disjunction of its realization bases. This consequence undermines the alethic functionalists’ non-deflationary ambitions. A plausible response to Kim’s argument fails to carry over to alethic functionalism on account of significant differences between alethic functionalism and psychological functionalism. Lynch’s revised view in his book Truth as One and Many (2009) fails to answer our challenge. The upshot is that, while mental functionalism may survive Kim’s argument, it mortally wounds functionalism about truth.
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Notes
Our argument does not address the question whether the concept of truth is a functional concept. Rather, as with Kim’s argument, our argument targets the claim that the property of truth is a multiply realizable property.
Davidson (2001), for example, defends a primitivist account of truth.
This terminology comes from Antony and Levine (1997). We discuss their view in the objections and replies below.
For the most recent discussion of the platitudes, or “truisms,” and their role in specifying a theory of truth, see Lynch (2009: 70–3).
Lynch explicitly acknowledges the parallel: “By acknowledging that truth is always and everywhere the property of playing the truth role, functionalism is not abandoning pluralism. Consider the case of a mental state like pain. According to functionalist accounts that take pain as a (higher-order) role property, there is indeed a sense in which the nature of pain is uniform across species. This is because, by and large, the pain role is uniform across species. But explaining that role does not explain what pain is in a more fundamental sense. It does not explain how that function is performed in a particular organism. For that, we must look to the details of the organism's neuronal structure: we must look for the lower-level property that realizes the pain role. In the same way, the functional role of truth does explain how that role is filled in a particular discourse. For the underlying nature of truth, we must look to the details of the type of thought in question” (2001: 735).
This paragraph paraphrases Lynch (2001: 732–5) and (2004:393–5).
On the concession for fallibility see Lewis (1972).
Lewis calls this the “postulate” of our theory (1972: 253). ‘A’ stands for our sentence, the theoretically significant terms of which are listed parenthetically to the right.
To follow Lewis explicitly one would need to change ‘true’ and its cognates into names.
Lynch introduces these terms in discussing the weight principles of one discourse receive relative to other principles in the alethic network. Discourses without at least one near perfect realizer of truth or with more than one are unalethic, that is, the propositions in them are neither true nor false (Lynch 2001: 739f; 2009: 77).
It might turn out to be so on the assumption that a difference in extension entails a difference in concepts.
Recently, Lynch has rejected this specification of the property of truth (Lynch 2009: 66 and 66n18). We consider the newest formulation below. As will become apparent, our reasons for rejecting the older formulation differ from his.
Lynch (2009: 75) accepts a view of property identity whereby two properties are distinct just in case they are individuated by “non-identical sets of essential features and relations.” This leaves it open whether the essential features are causal.
Lynch (2005: 42n9) grants that his view implies that truth is necessarily co-extensive with some disjunctive property while denying the stronger identity claim.
We address non-causal explanatory features below.
We are grateful to Adam Podlaskowski for pressing this objection.
Strictly speaking, the view might turn into a form of “minimalism,” akin to Crispin Wright’s (1992). Wright, however, does not think there is a unique property meeting the general criteria for a predicate’s counting as a truth predicate. Because Lynch eschews pluralism, we do not discuss this option.
Lynch explicitly accepts the challenge of providing robust explanations involving truth (Lynch 2009). This demonstrates that specifying platitudes or truisms is not enough. One must also show that something plays the role as specified. We turn to this below.
Lynch does claim that in any possible world where ‘truth’ refers at all that it refers to the property with the features specified by the platitudes, i.e., to the property with the “truish features” (2009: 78). It is not claimed that all realizers, or manifesting properties, of truth, are present in every possible world.
We turn to Lynch’s discussion of the success argument below, which aims to tackle this concern.
Lynch (2009: 70) provides a list.
Note the domain variable. On Lynch’s account each proposition is tagged to a domain.
Lynch recognizes there are differences between the two views, however. For one, truth, when present, manifests itself, but a determinable does not manifest itself. Second, determinants “differ from one another along some linear ordering.” And third, “determinants of a determinable mutually detest one another” (2009: 75, 75n4).
It might be suggested that reading ‘or’ in an inclusive sense avoids this choice. Yet doing so threatens to overdetermine the causal role, for then in each case there would be two properties playing the role, truth and the manifesting property. Why posit two when one will suffice? Thanks to Cory Wright for pointing us to this possibility.
The full scenario is described in Lynch (2009: 122).
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Acknowledgments
For comments on earlier drafts, we are grateful to Clare Batty, Kamper Floyd, Eric Loomis, Michael Lynch, Adam Podlaskowski, Chase Wrenn, Cory Wright, and the audience at the 2008 Alabama Philosophical Society Meeting.
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Horton, M., Poston, T. Functionalism about Truth and the Metaphysics of Reduction. Acta Anal 27, 13–27 (2012). https://doi.org/10.1007/s12136-010-0105-x
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DOI: https://doi.org/10.1007/s12136-010-0105-x