Determining Relevance: Close Enough is Good Enough

Determining Relevance: Close Enough is Good Enough Sheldon J. Chow (schow55@uwo.ca) Department of Philosophy, Stevenson Hall, The University of Western Ontario London, Ontario, N6A 5B8 Canada Abstract when cognitive demands are high and/or when cognitive re- sources are low. Nevertheless, humans characteristically ex- hibit reasonable levels of success at identifying representa- tions which are relevant to the task at hand. Such reasonable levels of success cannot be ascribed to chance or luck. There- fore, we are left to explain how humans (seem to) solve the relevance problem, short of considering the totality of one’s beliefs (Fodor, 1987, 2000). However, the inquiry into how relevance is determined is constrained by how relevance is defined. Indeed, whether and the extent to which relevant representations are picked out and brought to bear on a cognitive task will depend on what property we are concerned with. Yet, defining relevance is not an easy task. In this paper I provide a cursory overview of what is arguably the most influential account of relevance to date, namely Sperber and Wilson’s Relevance Theory. I will then be able to use their Relevance Theory as a basis from which to propose an understanding of relevance that is sup- ported by a view of concepts and cognition which draws on current theories in cognitive science, as well as Fred Dretske’s information-theoretic epistemology. 1 This will allow me to show how relevance, or something like it, can be understood as naturally arising from human cognitive architecture, thus enabling the characteristic performance we observe in human reasoning. Humans exhibit characteristic success in considering what is relevant in their cognitive tasks. Yet understanding how rel- evance is determined in cognition remains a problem. This paper seeks to make headway on this problem. The relevance problem is first introduced. Sperber and Wilson’s influential theory of relevance is then discussed, but dismissed as inade- quate. Some conditions are identified that an adequate defini- tion of relevance might reasonably be expected to satisfy. A novel way to conceive of relevance is suggested which proves to be useful in understanding human cognitive performance. Keywords: Relevance; concepts; file model; cognitive archi- tecture. The Relevance Problem A longstanding problem in philosophy and cognitive science is understanding how we determine what is relevant to our cognitive tasks. The cognitive systems paradigmatically re- sponsible for general reasoning and decision-making—so- called central systems—admittedly allow for free exchange of information. A dream of a snake biting its own tail, for example, bore in interesting and important ways on Kekul´e’s theorizing of the benzene molecule. A consequence of such a free exchange of information, however, is that, provided an appropriate set of background beliefs, any representation held by an agent can in principle be relevant to a given cog- nitive task in central cognition. Who won tonight’s football game is prima facie irrelevant to whether there is beer in your friend’s fridge. But if you believe that your friend’s favourite football team played tonight, and that your friend usually overindulges in beer consumption whenever his favourite team wins, then your belief about who won tonight’s game actually is relevant to your belief about beer in your friend’s fridge. Since relevance can be determined only with respect to one’s background beliefs, there is no way to circumscribe a priori the subset of representations that are relevant in a given occasion of reasoning or inference. Let us express this problem thus: Sperber and Wilson’s Relevance Theory Sperber and Wilson (1986/1995) developed their Relevance Theory in the context of communication and pragmatics. Hu- mans tend to have an easy time communicating with each other, despite the fact that the meanings of utterances are enormously underdetermined. A simple example: Alice says to Bob, “Isn’t that cute? ” while nodding toward a chipmunk scurrying up a tree; Bob knows that by “that” Alice is re- ferring to the chipmunk, and not to the birds in the other branches, the tree itself, or whatever else was within his per- ceptual field at the time of her utterance. According to Sper- ber and Wilson (SW henceforth), Bob understands that Alice was referring to the chipmunk because the stimulus of the The relevance problem How a cognitive system con- siders only what is (mostly) relevant, or equivalently, how a cognitive system knows what is relevant. 1 It should be kept in mind throughout the discussion that I am not intending to develop a full theory of relevance. I therefore do not offer any claim of completeness. Such a task deserves a more extensive treatment than what I can provide in this short paper. My contribution might be understood as a useful preliminary discussion of how the problem of relevance might be stated, and an identifi- cation of some conditions that an adequate definition of relevance might reasonably be expected to satisfy. Nevertheless, I shall sug- gest a potential way to conceive of relevance which proves to be useful in understanding human cognitive performance. Despite the fact that the relevance problem introduces a computational problem of sifting through heaps of informa- tion to decide what bears on the task at hand, humans seem to determine what is relevant in their cognitive tasks quickly and rather easily. This is not to say that we always know and con- sider what is relevant. For we often fail to do so, especially