Psychologism and Metalogic

This paper examines two arguments againstpsychologism advanced by Frege andHusserl. The first argument says that thelaws of logic cannot be justified by thelaws of psychology, because the formerand a priori and certain, but the latterare probable only. The second argumentpoints out that the status of logicallaws as universal principles of thinking isnot intelligible on the psychologisticinterpretation of logic. The author tries toshow how to examine both arguments bymetalogical devices.     

Applied Logic without Psychologism

Logic is a celebrated representation language because of its formal generality. But there are two senses in which a logic may be considered general, one that concerns a technical ability to discriminate between different types of individuals, and another that concerns constitutive norms for reasoning as such. This essay embraces the former, permutation-invariance conception of logic and rejects the latter, Fregean conception of logic. The question of how to apply logic under this pure invariantist view is addressed, and a methodology is given. The pure invariantist view is contrasted with logical pluralism, and a methodology for applied logic is demonstrated in remarks on a variety of issues concerning non-monotonic logic and non-monotonic inference, including Charles Morgan’s impossibility results for non-monotonic logic, David Makinson’s normative constraints for non-monotonic inference, and Igor Douven and Timothy Williamson’s proposed formal constraints on rational acceptance.     

A Challenge to Divine Psychologism

Alvin Plantinga proposes that mathematical objects and propositions are divine thoughts. This position, which I call divine psychologism, resonates with some remarks by contemporary thinkers. Plantinga claims several advantages for his position, and I add another: it helps to explain the glory of mathematics. But my main purpose is to issue a challenge to divine psychologism. I argue that it has an implausible consequence: it identifies an entity with God's relation to that entity. I consider and rebut several ways in which a divine psychologist might argue that this is not really a consequence, or that the identification is plausible.     

Psychologism, Practical Reason and the Possibility of Error

Psychologism is the view that practical reasons are psychological states. It is widely thought that psychologism is supported by the following principle governing explanation:
TF. The difference between false and true beliefs on A's part cannot alter the form of the explanation which will be appropriate to A's actions. (TF) seems to imply that we always need to cite agents' beliefs when explaining their actions, no matter whether those beliefs are true or false. And this seems to vindicate psychologism. I argue, however, that the standard argument for psychologism which includes (TF) as a premise in fact fails to establish its intended conclusion. As a result, the overall case for psychologism is not as strong as it may initially seem.     

Psychologism Revisited in Logic, Metaphysics, and Epistemology

Psychologism is a philosophical ideology that seeks to explain the principles of logic, metaphysics, and epistemology as psychological phenomena. Psychologism has been the storm center of concerted criticisms since the nineteenth century, and is thought by many to have been refuted once and for all by Kant, Frege, Husserl, and others. The project of accounting for objective philosophical or mathematical truths in terms of subjective psychological states has been largely discredited in mainstream analytic thought. Ironically, psychologism has resurfaced in unexpected guises in the form of intuitionistic logic and mathematics, cognitivism, and naturalized epistemology. I examine some of the principal objections to psychologism – distinguishing roughly between good and bad or philosophically acceptable versus unacceptable psychologism – and consider the extent to which a new wave of psychologism may be gaining prominence in contemporary philosophy, and the light its successes and failures may shed on the original concept and underlying perspective of classical psychologism.     

The Case for Psychologism in Default and Inheritance Reasoning

Default reasoning occurs whenever the truth of the evidence available to the reasoner does not guarantee the truth of the conclusion being drawn. Despite this, one is entitled to draw the conclusion “by default” on the grounds that we have no information which would make us doubt that the inference should be drawn. It is the type of conclusion we draw in the ordinary world and ordinary situations in which we find ourselves. Formally speaking, ‘nonmonotonic reasoning’ refers to argumentation in which one uses certain information to reach a conclusion, but where it is possible that adding some further information to those very same premises could make one want to retract the original conclusion. It is easily seen that the informal notion of default reasoning manifests a type of nonmonotonic reasoning. Generally speaking, default statements are said to be true about the class of objects they describe, despite the acknowledged existence of “exceptional instances” of the class. In the absence of explicit information that an object is one of the exceptions we are enjoined to apply the default statement to the object. But further information may later tell us that the object is in fact one of the exceptions. So this is one of the points where nonmonotonicity resides in default reasoning. The informal notion has been seen as central to a number of areas of scholarly investigation, and we canvass some of them before turning our attention to its role in AI. It is because ordinary people so cleverly and effortlessly use default reasoning to solve interesting cognitive tasks that nonmonotonic formalisms were introduced into AI, and we argue that this is a form of psychologism, despite the fact that it is not usually recognized as such in AI. We close by mentioning some of the results from our empirical investigations that we believe should be incorporated into nonmonotonic formalisms.     

Wittgenstein and Nonsense: Psychologism,Kantianism, and the Habitus

This paper is a critical examination of Wittgenstein's view of the limits of intelligibility. In it I criticize standard analytic readings of Wittgenstein as an advocate of transcendental or behaviourist theses in epistemology; and I propose an alternative interpretation of Wittgenstein's view as a social contextualism that transcends the false dichotomy between Kantianism and psychologism. I argue that this social contextualism is strikingly similar to the social account of epistemic practices developed by Pierre Bourdieu. Through a comparison between Wittgenstein's and Bourdieu's view and an analysis of the notion of habitus , I try to show how social contextualism can account for the distinction between sense and nonsense without falling into transcendental constructivism or social behaviourism.     

Psychologism as a style of reasoning and the study of persons

“Psychologism” is proposed as a “style of reasoning” dominant in psychology that has set the agenda for determining what counts as psychological phenomena, their nature, and how they are to be investigated and understood. The assumptions of psychologism and particularities of its procedure are detailed and, subsequently, illustrated by example using the psychological study of attitudes. The failure of psychologism is raised and an alternative to the conception of persons implicit in psychologism is discussed as an initial step in forging a style of reasoning adequate to psychological inquiry.     

Completeness and super-valuations

This paper uses the notion of Galois-connection to examine the relation between valuation-spaces and logics. Every valuation-space gives rise to a logic, and every logic gives rise to a valuation space, where the resulting pair of functions form a Galois-connection, and the composite functions are closure-operators. A valuation-space (resp., logic) is said to be complete precisely if it is Galois-closed. Two theorems are proven. A logic is complete if and only if it is reflexive and transitive. A valuation-space is complete if and only if it is closed under formation of super-valuations.     

External World Skepticism,Confidence and Psychologism about the Problem of Priors

In this paper, I will distinguish two varieties of external world skepticism: belief and confidence skepticism. I will argue that we can defang the intuitive motivations for confidence skepticism (though not a meeker “argument from might,” which got some attention in the twentieth century literature on external world skepticism) by adopting a partially psychologistic answer to the problem of priors. And I will argue that certain recent work in the epistemology of mathematics and logic provides independent support for such psychologism.