Perceptual Intuitionism

In the recent metaethical literature there has been significant interest in the prospects for what I am denoting ‘Perceptual Intuitionism’: the view that normal ethical agents can and do have non‐inferential justification for first‐order ethical beliefs by having ethical perceptual experiences, e.g., Cullison 2010, McBrayer 2010, Vayrynen 2008. If true, it promises to constitute an independent a posteriori intuitionist epistemology, providing an alternative to intuitionist accounts which posit a priori intuition and/or emotion as sources of non‐inferentially justified ethical beliefs. As it is formulated, it is plausible that a necessary condition for the view is the truth of Ethical Perception: normal ethical agents can and do have perceptual experiences (at least some of which are veridical) as of the instantiation of ethical properties. In this paper a sophisticated and promising account of Ethical Perception is offered. Extant objections are shown to fail. However, it will be argued that it is far from obvious that the account of Perceptual Intuitionism which emerges constitutes an independent alternative to other intuitionist accounts. This is because we have reason to think that ethical perceptual experience may be epistemically dependent on other epistemic sources, e.g. a priori intuition or emotion.     

Clarifying Ethical Intuitionism

In recent years there has been a resurgence of interest in Ethical Intuitionism, whose core claim is that normal ethical agents can and do have non‐inferentially justified first‐order ethical beliefs. Although this is the standard formulation, there are two senses in which it is importantly incomplete. Firstly, ethical intuitionism claims that there are non‐inferentially justified ethical beliefs, but there is a worrying lack of consensus in the ethical literature as to what non‐inferentially justified belief is. Secondly, it has been overlooked that there are plausibly different types of non‐inferential justification, and that accounting for the existence of a specific sort of non‐inferential justification is crucial for any adequate ethical intuitionist epistemology. In this context, it is the purpose of this paper to provide an account of non‐inferentially justified belief which is superior to extant accounts, and, to give a refined statement of the core claim of ethical intuitionism which focuses on the type of non‐inferential justification vital for a plausible intuitionist epistemology. Finally, it will be shown that the clarifications made in this paper make it far from obvious that two intuitionist accounts, which have received much recent attention, make good on intuitionism's core claim.     

Challenges to Audi's Ethical Intuitionism

Robert Audi's ethical intuitionism (Audi, 1997, 1998) deals effectively with standard epistemological problems facing the intuitionist. This is primarily because the notion of self-evidence employed by Audi commits to very little. Importantly, according to Audi we might understand a self-evident moral proposition and yet not believe it, and we might accept a self-evident proposition because it is self-evident, and yet fail to see that it is self-evident. I argue that these and similar features give rise to certain challenges to Audi's intuitionism. It becomes harder to argue that there are any self-evident propositions at all, or more than just a few such propositions. It is questionable whether all moral propositions that we take an interest in are evidentially connected to self-evident propositions. It is difficult to understand what could guide the sort conceptual revision that is likely to take place in our moral theorising. It is hard to account for the epistemic value of the sort of systematicity usually praised in moral theorising. Finally, it is difficult to see what difference the truth of Audi's ethical intuitionism would make to the way in which we (fail to) handle moral disagreement.     

Intuitionism,Meaning Theory and Cognition

Michael Dummett has interpreted and expounded upon intuitionism under the influence of Wittgensteinian views on language, meaning and cognition. I argue against the application of some of these views to intuitionism and point to shortcomings in Dummett's approach. The alternative I propose makes use of recent, post-Wittgensteinian views in the philosophy of mind, meaning and language. These views are associated with the claim that human cognition exhibits intentionality and with related ideas in philosophical psychology. Intuitionism holds that mathematical constructions are mental processes or objects. Constructions are, in the first instance, forms of consciousness or possible experience of a particular type. As such, they must be understood in terms of the concept of intentionality. This view has a historical basis in the literature on intuitionism. In a famous 1931 lecture Heyting in fact identifies constructions with fulfilled or fulfillable mathematical intentions. I consider some of the consequences of this identification and contrast them with Dummett's views on intuitionism.     

On A Neglected Path to Intuitionism

According to Quine, in any disagreement over basic logical laws the contesting parties must mean different things by the connectives or quantifiers implicated in those laws; when a deviant logician ‘tries to deny the doctrine he only changes the subject’. The standard (Heyting) semantics for intuitionism offers some confirmation for this thesis, for it represents an intuitionist as attaching quite different senses to the connectives than does a classical logician. All the same, I think Quine was wrong, even about the dispute between classicists and intuitionists. I argue for this by presenting an account of consequence, and a cognate semantic theory for the language of the propositional calculus, which (a) respects the meanings of the connectives as embodied in the familiar classical truth-tables, (b) does not presuppose Bivalence, and with respect to which (c) the rules of the intuitionist propositional calculus are sound and complete. Thus the disagreement between classicists and intuitionists, at least, need not stem from their attaching different senses to the connectives; one may deny the doctrine without changing the subject. The basic notion of my semantic theory is truth at a possibility, where a possibility is a way that (some) things might be, but which differs from a possible world in that the way in question need not be fully specific or determinate. I compare my approach with a previous theory of truth at a possibility due to Lloyd Humberstone, and with a previous attempt to refute Quine’s thesis due to John McDowell.     

What Anit-realist Intuitionism Could Not Be

One of the two major parts of Dummett’s defense of intuitionism is the rejection of classical in favor of intuitionistic reasoning in mathematics, given that mathematical discourse is anti-realist. While there have been illuminating discussions of what Dummett’s argument for this might be, no consensus seems to have emerged about its overall form. In this paper I give an account of this form, starting by investigating a fundamental, but little discussed question: to what view of the relation between deductive principles and meaning is anti-realism committed? The result of this investigation is a constraint on meaning theoretic assessments of logical laws. Given this constraint, I show that, surprisingly, a consistent anti-realist critique of classical logic could not rely on the rejection of bivalence. Moreover, a consistent anti-realist defense of intuitionism must begin with a radical rejection of the very conception of logical consequence that underlies realist classical logic. It follows from these conclusions that anti-realist intuitionism seems committed to proceeding by proof theoretic means.     

Intuitionism: An introduction to a seminar

Journal of Philosophical Logic -     

Intuitionism and the Modal Logic of Vagueness

Journal of Philosophical Logic - Intuitionistic logic provides an elegant solution to the Sorites Paradox. Its acceptance has been hampered by two factors. First, the lack of an accepted semantics...