The notion of rationality is crucial to Computer Science and Artificial Intelligence, Economics, Law, Philosophy, Psychology, Anthropology, etc. Most if not all of these disciplines presuppose the agent's capacity to infer in a logical manner. Theories about rationality tend toward two extremes: either they presuppose an unattainable logical capacity, or they tend to minimize the role of logic, in light of vast data on fallacious inferential performance. We analyze some presuppositions in the classical view of logic, and suggest empirical and (...) theoretical evidence for the place of inferential heuristics in a theory of rationality. We propose (1) to outline a new theory of rationality that includes the key notion of logical capacity as a necessary but realistic factor, (2) to expand the notion of inference to include non-deductive inference, specifically non-monotonic, and (3) to emphasize the logical role of inferential heuristics and constraints such as cognitive economy. (shrink)

One of philosophy’s oldest paradoxes is the apparent contradiction between the great triumphs and the dramatic failures of the human mind. The same organism that routinely solves inferential problems too subtle and complex for the mightiest computer often makes errors in the simplest of judgments about everyday events. (Nisbett and Ross 1980, p. xi).

Belief attributions pose difficult problems for the semantics of natural languages. One problem is to give an account of the "objects" of belief that respects the logical opacity of belief . Another problem is to respect the partial deductive closure of belief: the fact that belief attribution presupposes that believers draw some, but not all, logical consequences from their beliefs. On standard theories, however, partial deductive closure seems to imply total deductive closure. ;I critically examine the major semantic theories of (...) belief attributions--among others those due to Russell, Cresswell, Fodor, and Stalnaker--and argue that their defects are rooted in the framework in which they are constructed. I propose an alternative framework, one that is built on the following two ideas: Objects of belief are not to be identified with the meanings of sentences. I propose that they be identified with "Informational Contents". Informational Contents, as I conceive of them, are abstract, language independent entities whose individuation is sensitive to the logical and semantic complexity of the that-clauses, and to pragmatic and psychological parameters. The partial deductive closure of our beliefs, I suggest, be accounted for by treating 'believe' as a vague predicate--a predicate that is tolerant of marginal changes in the conceptual and logical complexity of its objects. I argue that the problem of partial deductive closure is parallel to that of the Sorites paradox, and should be solved in a parallel way. ;The framework suggested by these two ideas will yield, I believe, an adequate semantic theory of belief sentences, one that reflects the underlying presuppositions of ordinary usage. (shrink)

One of the key concepts in the Philosophy of Logic is the notion of inference. In this paper we expand the notion of logical inference and describe its role in a comprehensive theory of rationality. Some recent rationality theories either presuppose an unattainable logical capacity or they minimize the role of logic, in light of the vast amount of data on fallacious inferential performance. In this paper we defend the view that logical acuity, redefined to include heuristics, is a necessary (...) factor in rationality. We evaluate some presuppositions of algorithmic models and some normative and metatheoretical properties of heuristic models, and defend our model against possible objections. Our revised notion of logical inference functions as the nucleus of the notion of logical acuity which in turn is a necessary building block for a realistic model of rationality. This model emphasizes the logical role of inferential heuristics, cognitive constraints and contextuality, introduces concepts such as "obvious inference", "cautious deductive closure", and "familiarity", and develops the notions of cognitive economy and contextual limitations as tools for evaluating and predicting rational behavior. (shrink)

One of the key concepts in the Philosophy of Logic is the notion of inference. In this paper we expand the notion of logical inference and describe its role in a comprehensive theory of rationality. Some recent rationality theories either presuppose an unattainable logical capacity or they minimize the role of logic, in light of the vast amount of data on fallacious inferential performance. In this paper we defend the view that logical acuity, redefined to include heuristics, is a necessary (...) factor in rationality. We evaluate some presuppositions of algorithmic models and some normative and metatheoretical properties of heuristic models, and defend our model against possible objections. Our revised notion of logical inference functions as the nucleus of the notion of logical acuity which in turn is a necessary building block for a realistic model of rationality. This model emphasizes the logical role of inferential heuristics, cognitive constraints and contextuality, introduces concepts such as "obvious inference", "cautious deductive closure", and "familiarity", and develops the notions of cognitive economy and contextual limitations as tools for evaluating and predicting rational behavior. (shrink)