Online research in philosophy

This paper investigates whether there is an acceptable version of Functionalism that avoids commitment to second-order properties. I argue that the answer is “no”. I consider two reductionist versions of Functionalism, and argue that both are compatible with multiple realization as such. There is a more specific type of multiple realization that poses difficulties for these views, however. The only apparent Functionalist solution is to accept second-order properties.

Saul Kripke has proposed an argument to show that there is a serious problem with many computational accounts of physical systems and with functionalist theories in the philosophy of mind. The problem with computational accounts is roughly that they provide no noncircular way to maintain that any particular function with an infinite domain is realized by any physical system, and functionalism has the similar problem because of the character of the functional systems that are supposed to be realized by organisms. This paper shows that the standard account of what it is for a physical system to compute a function can avoid Kripke's criticisms without being reduced to circularity; a very minor and natural elaboration of the standard account suffices to save both functionalist theories and computational accounts generally.

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.

There is an argument for functionalism—and _ipso facto_ against identity theory—that can be sketched as follows: We are, or want to be, or should be dedicated to functional explanations in the sciences, or at least the special sciences. Therefore—according to the principle that what exists is what our ideal theories say exists—we are, or want to be, or should be committed to metaphysical functionalism. Let us call this the _argument from functional_ _explanation_. I will try to reveal the motivation for making such an argument, and sketch the kind of response that should be made by critics of functionalism.

Which comes first, realization or multiple realization? Hilary Putnam (1960) invoked the term ‘realization’ to refer to the relation that holds between physical devices and abstract computing machines, such as Turing machines or probabilistic automata. Putnam (1967) hypothesized that the relation between brain and mind is also realization. He contrasted his hypothesis—which he dubbed “functionalism”—with the competing hypotheses that mental states are to be identified with syndromes of behavior and behavioral dispositions, or that mental states are to be identified with brain processes. Instead, functionalism proposes that mental states are to be identified with functional states of whole organisms. Importantly, Putnam regards functionalism as an empirical hypothesis, and one whose explication appeals to some technical notions, particularly to the idea of a probabilistic automaton.

Saul Kripke has proposed an argument to show that there is a serious problem with many computational accounts of physical systems and with functionalist theories in the philosophy of mind. The problem with computational accounts is roughly that they provide no noncircular way to maintain that any particular function with an infinite domain is realized by any physical system, and functionalism has the similar problem because of the character of the functional systems that are supposed to be realized by organisms. This paper shows that the standard account of what it is for a physical system to compute a function can avoid Kripke's criticisms without being reduced to circularity; a very minor and natural elaboration of the standard account suffices to save both functionalist theories and computational accounts generally.