The Is-Ought Gap

Survey talk delivered to the Cambridge Meta-Ethics group in 2011. After some brief remarks on the ambiguities in Hume's version of No-Ought-From-Is, I outline Prior's paradox and discuss the various responses, principally mine (the New Zealand Plan) and Schurz's (the Austrian Plan). In this text I add seven appendices drawn mainly from my introduction to Hume On Is and Ought, amplifying the argument, discussing matters arising and outlining rival approaches to the problem, principally the relevantist solution, due to Ed Mares, and the Inference Barrier solution (the Scottish/Australian Plan) due to Gillian Russell and Greg Restall. I also discuss the work of Stephen Maitzen and Mark Nelson. In this talk I emphasize the logical aspects of the issue. Drafts of my contributions to this debate available above in 'Papers'. 'The Triviality of Hume's Law', 'Coda: Truth and Consequences' and 'Subtance, Taxonomy, Content and Consequence' emphasize the logical and meta-ethical aspects of the the issue, whilst 'Letter From a Gentleman' and 'Snare's Puzzle/Hume's Purpose' emphasize meta-ethics and the historical Hume. 'Comments on "Hume's Master Argument"' deals with all three themes. The kick-off paper is 'Logic and the Autonomy of Ethics' (1989). The last in the sequence is 'Hume on is and Ought: Logic Promises and the Duke of Wellington'.

Journal of Philosophical Logic, 1991

Hume's famous is-ought thesis (cf. Hume, 1739/40, p. 469) saying that nothing about what ought (or ought not) to be the case can be deduced from what is (or is not) the case, was the object of a continu- ing philosophical debate, without leading to agreement (cf. Hudson, 1969). ...

2000

A logical investigation of the Is-Ought problem is in a subtle position with respect to the question of ethical cognitivism. It has to presuppose at certain portion of cognitivism, but it has to remain ignorant with respect to rest of it. Let me therefore start my talk with a differentiation in the concept of cognitivism. What a logical investigation of the Is-Ought problem has to assume is what I call (1.) Semantic Cognitivism: (a) Normative (ethical) assertions have semantical contents which can be represented as propositions, and (b) these propositions can be semantically evaluated by a meta-logical 'truth' or 'correctness' predicate.

Charles R ed. (2010) Hume on ‘Is’ and ‘Ought’, Houndmills, Palgrave, pp. 1-38. , 2010

This contains 1) A methodological meditation in blank verse, defending a broadly collegial vision of the history of philosophy, as applied specifically to Hume. 2) A conspectus of the debate on the role of No-Ought-From-Is within the Treatise itself. What does Hume mean by ‘deduction’ and are the deductions from Is to Ought actually or only seemingly inconceivable? Why after having made so much of NOFI in the Treatise does Hume drop it in the EPM? 3) A summary of the debate surrounding Heathcote’s contention that NOFI is an instance of Hume’s Ockhamist ‘Master Argument’. 4) A potted history of the reception of NOFI from Reid and Bentham to Hudson. 4) A conspectus of the debate on the meta-ethical implications of NOFI, specifically targeting the idea that it implies either non-naturalism, non-cognitivism, expressivism or a fact/value split (I say ‘none of the above’). 5) A survey of four major responses to Prior’s famous counterexamples both to NOFI and to the conservativeness of logic (the thesis that in a valid argument you don’t get out what you haven’t put in). These are the New Zealand Plan (due to me) which devises and proves an amended version of NOFI (No-Non-Vacuous-Ought-From-Is), the Austrian Plan (due to Gerhard Schurz) which devises and proves another version of NOFI (No-Ought-Relevant-Ought-From-Is), the Scottish/Australian Plan (due to Gillian Russell and Greg Restall) which defends a revised version of NOFI by constructing and proving an implication barrier thesis, and the relevantist solution, (represented in this collection by Edwin Mares) which defeats Prior’s dilemma by lopping off one of its horns. 6) A summary of the debate about Stephen Maitzen’s interesting claim that though it may be impossible to derive substantively moral conclusions from FORMALLY non-moral premises, it is possible to derive substantively moral conclusions from SUBSTANTIVELY non-moral premises, thus rendering the formal proofs of his opponents redundant. (I say his argument presupposes an implausible form of taxonomic essentialism.)

Auslegung: a Journal of Philosophy, 1981

Cambridge University Press eBooks, 2018

With Hume's texts I follow a slight variation on the Hume Society's system of reference: title, book, section, and paragraph numbers followed by page references to the Selby-Bigge/Nidditch or Miller editions, following a forward slash.

This paper dispels a misconception that has haunted western philosophy for nearly three hundred years, the idea that you cannot infer "ought" statements from "is" statements. In fact you can, quite easily. The “ought” is a hypothetical imperative, a prudential recommendation, not a categorical, universal, or moral imperative. But it is an “ought” nevertheless, and of great practical import.

Sanne Taekema, Bart van Klink and Wouter de Been (eds.), Facts and Norms in Law, Edward Elgar 2016, p. 23-49, 2016

Philosophical and methodological discussions with regard to normative and value judgment presuppose the availability of a set of clear concepts by means of which these discussions can be made fruitful. To provide such a framework, or at least its beginnings, the present paper makes and explains distinctions between, amongst others, facts and descriptions thereof, kinds of objectivity of facts, deontic facts and norms, kinds of deontic facts, kinds of rules, and facts and values. By means of some examples, the usefulness of the clear concepts for methodological issues is illustrated.

Argumentation, 2000

Many philosophers claim that no formally valid argument can have purely non-normative premises and a normative or moral conclusion that occurs essentially. Mark Nelson recently proposed a new counterexample to this Humean doctrine: