An explanatory approach to behavior and the constitution of cognitive states that regards particular behaviors and cognitive structures and capacities as playing functional roles in particular domains or contexts. See also functionalism(1), causal functionalism, explanation.

Functionalism (2) is an explanatory approach to behavior and cognition that assumes the framework of evolutionary biology. Consequently, functionalism (2) regards specific behaviors and faculties or capacities as playing correspondingly specific and adaptive functional roles in the lives of the individuals and/or species that evidence them.
Functionalism (2) differs from the functionalism, sometimes designated as "input-output functionalism," that often appears in the literature of cognitive science and philosophy of mind. This latter functionalism may be described as holding that the defining characteristic of a mental state is the set of causal relations it bears to inputs, other mental states, and outputs. Functionalism (2), by contrast, can be described as a quasi-teleological theory of adapted faculties and their functions.
Defining a Function
Functionalism (2) assumes a definition of function that, following Wright (1973/1995, p. 42), can be stated as:
The function of _X_ is _Z_ means (a) _X_ is there because it does _Z_, (b) _Z_ is a consequence (or result) of _X_'s being there
In other words, for an organism _O_, the function of faculty or organ _X_ is that particular thing _Z_ that _X_ is good for and that explains why _O_s have _X_s.
This conception of a function is meant to capture two central ideas: first, that _Z_ is a function proper of _X_ and not merely an accidental consequence or by-product of _X_, and second, that _X_ is selected by virtue of its doing _Z_. This latter feature is what Wright calls "consequence-selection," or "selection by virtue of resultant advantage" (1973/1995, p. 43).
The Interaction and Isolation of Functions
Although under ordinary circumstances an organism's various functions can be expected to interact, individual functions are hypothesized to have been shaped by the pressures of the specific domains in which the organism is active. It is in terms of such discrete domains that specific functions can be approached, or, as Reber puts, we can only understand a given behavior or capacity by "recognizing the role of the conditions under which it emerged and the functions that it has" (Reber 1995, p. 156). This has a practical consequence in that attempts to study individual functions will be carried out within domains contrived as narrowly as possible, in order that the target function can be brought to the foreground to the greatest extent. One such attempt at the experimental isolation of a given function can be found in the artificial grammar learning experiments carried out by Reber and others. For these experiments the researchers designed situations meant to articulate effects that could be attributed to a single function, that is, the cognitive faculty hypothesized to afford acquisition of a grammar.
It should be emphasized, however, that the isolation of a function under experimental conditions is no more than a pragmatic expedient. A fuller, more natural account of the isolated function would have to locate it within the context of various interacting functions, the sum of which make up an organism's complex repertoire of capacities and behaviors. But functional isolation does buy us a measure of understanding in that it allows us to model the components making up an organism's cognitive and behavioral resources. Admittedly, the models resulting from functional isolation are necessarily idealizations of the actual processes and faculties under consideration. But as with all such idealizations, these models allow us to try to carve an organism's various functions at the joints.
Functionalism and Adaptation
Like input-output functionalism, functionalism (2) is subject to intentionalist criticism of the type found in Searle (1992). According to this critique, ascribing a function to a faculty or organ is always done against a background of the ascriber's intentions (1992, p. 237). The conclusion to be drawn is that the functional ascription is therefore not intrinsic to the faculty or organ, but rather to the teleology imposed on it from the outside by the observer. However, in the case of functionalism (2) it may be argued that consequence selection answers this concern. As Wright notes (1973/1995, p. 43), framing selection in terms of resulting advantage effectively separates selection from any necessary dependence on volition. For if the function is selected on the basis of the relative adaptive advantage it brings its possessor, we need only say that it is adaptive pressure of whatever sort that determines selection. If this is the case, then ascriptions of function can be taken as hypotheses about the intrinsic properties of a faculty or organ, which are in turn necessarily constrained by the best available theory of what counts as adaptive.
It is worth noting, however, that consequence selection can also accommodate functions that are in fact intentionally selected or designed. Consciously designed functions, no less than naturally selected functions, are functions "by virtue of their being the reason the thing with the function `is there'" (Wright 1973/1995, p. 43). In sum, consequence selection allows intentional design to define functions without mandating it as a necessary condition of function definition.
Implications for Representational Theory and Content Ascription
Functionalism (2) carries important implications for content ascription and for representational theories generally. Specifically, functionalism (2) requires that given limits be placed on exactly what content states can be ascribed to a person. As Reber points out, content ascriptions made under functionalism (2) are constrained less by pure representational theory than by an understanding of what it is for a person to behave in an adaptive manner (Reber 1995, p. 58). While functionalist (2) content ascriptions still will be formulated in terms of what it is possible for a person to represent, the understanding of what "possible" means in any given situation will be characterized in terms of specifically adaptive possibilities. In sum, under functionalism (2), our attribution of a given representational content to a person will be constrained by what it is possible for that person to represent, given that his or her behavior or cognitive state is an adaptive response to the domain or situation in question.
Daniel Barbiero