For the last 40 years or so the is/ought gap, the fact/value distinction and the naturalistic fallacy have figured prominently in ethical debates. This longevity, however, has had an adverse side effect. So familiar have they become that they—and their respective rationales—have tended to become blurred. It is the purpose of this paper to explain why they should be kept distinct.

This chapter focuses on one of the common fallacies in Western philosophy called the 'is/ought fallacy (IOF)'. Some philosophers conclude that the IOF is not a logical problem but an epistemological one, meaning that even if inferences like this one are logically valid, they cannot be used epistemologically to warrant anyone's real‐life moral beliefs. Arguments do not warrant their conclusions unless the premises of those arguments are themselves warranted, and in the real world, they say, no one would ever (...) be warranted in believing premise. Charles Pigden argues for the illegitimacy of the move from is to ought, saying that we should understand David Hume as pointing to the conservativeness of logic. According to Pigden, logic is conservative in that “the conclusions of a valid inference are contained within the premises. You do not get out what you have not put in”. (shrink)

Schurz draws on modern alethic- deontic predicate logic to address the venerable yet enduring problem of whether what ought to be can be derived from what is. After two extensive introductory chapters supplying the background in philosophy and logic to readers unfamiliar with it, he examines such dimensions as the logical explication of Hume's thesis, the special Hume thesis, weakened versions of it, generalizations, some applications to ethical arguments, problems of identity and existence, whether there are analytic bridge principles, (...) and whether they are scientifically justifiable. The inquiry is expanded from Part II of his 1989 Relevant Deduction in Science and Ethics with a Case Study of the Is-Ought Problem. No index. Annotation copyrighted by Book News, Inc., Portland, OR. (shrink)

Hume seems to claim that there does not exist a valid argument that has all non-ethical sentences as premises and an ethical sentence as its conclusion. Starting with Prior, a number of counterexamples to this claim have been proposed. Unfortunately, all of these proposals are controversial. Even the most plausible have a premise that seems like it might be an ethical sentence or a conclusion that seems like it might be non-ethical. Since it is difficult to tell whether any of (...) these counterexamples are genuine, we need a taxonomy that sorts out ethical sentences from non-ethical ones. We need to know the difference between an ‘Is’ and an ‘Ought’. In the first part of the paper, I establish the need for a taxonomy. I consider some of the most influential ‘Is’–‘Ought’ derivations. These include proposals by Prior and Searle. I argue that each proposal has a premise whose status as ethical or non-ethical is difficult to determine. In the second part of the paper, I consider taxonomies proposed by Karmo and Maitzen. I argue against both taxonomies. I end with the claim that we need a taxonomy of ethical sentences and that none of the current proposals are adequate. (shrink)

Book Information The Is-Ought Problem: An Investigation in Philosophical Logic. By Gerhard Schurz. Kluwer. Dordrecht. 1997. Pp. x + 332. £92.25.

The article deals with a recent attack by Sam Harris on two famous arguments that purport to establish a gap between factual and evaluative statements—Hume’s Is-Ought Problem and Moore’s Open Question Argument. I present the arguments, analyze the relationship between them and critically assess Harris’ attempt to refute them. I conclude that Harris’ attempt fails.

This article is concerned with the role empirical research can play in normative practical ethics. There is no doubt that ethical research requires some kind of collaboration between normative disciplines and empirical sciences. But many researchers hold that empirical science is only assigned a subordinate role, due to the doctrine that normative conclusions cannot be justified by descriptive premises. Scientists working in the field of ethics commonly hold, however, that the empirical sciences should play a much bigger role in ethical (...) research. The aim of this paper is to show that empirical sciences can play a substantive role in normative ethics, with no illicit inferences from is to ought. To achieve this aim, I explain Hume’s thesis. In the following sections, I am concerned with different uses of empirical data that do not imply an illicit inference from descriptive premises to a normative conclusion. The article demonstrates that there are many modes of ethical reasoning that allow for a substantive use of empirical data, and it also shows the importance of Hume’s thesis for clarifying ethical reasoning. (shrink)

The is-ought gap is Hume’s claim that we can’t get an ‘ought’ from just ‘is’s. Prior (“The Autonomy of Ethics,” 1960) showed that its most straightforward formulation, a staple of introductory philosophy classes, fails. Many authors attempt to resurrect the claim by restricting its domain syntactically or by reformulating it in terms of models of deontic logic. Those attempts prove to be complex, incomplete, or incorrect. I provide a simple reformulation of the is-ought gap that closely fits (...) Hume’s description of it. My formulation of the gap avoids the proposed counterexamples from Prior and offers a natural explanation of why they seem compelling. Moreover, I show that my formulation of the gap is guaranteed by standard theories of the semantics of normative terms, and that provides a more general reason to accept it. (shrink)

Focusing mainly on Meinong’s "Über emotionale Präsentation" and Veber’s "Die Natur des Sollens", I examine their respective conceptions of ought. Meinong has not written a specific work on the ought, he deals with it as a part of his value theory. In "Über emotionale Präsentation" the ought is a property of being, which cannot be viewed as separated from a desiring subject. The ought is an ideal object of higher order; it concerns neither factuality nor non-factuality, (...) but subfactuality, that is the realm of possibility. In "Die Natur des Sollens", Veber proposes a structured theory of ought, which is grounded on Meinongian concepts. The ought is the object of a volition, it is a genuine object, even though ideal. I conclude by portraying the differences between Veber's and Meinong's conceptions of the ought. (shrink)

Many take the claim that you cannot ‘get’ an ‘ought’ from an ‘is’ to imply that non- moral beliefs are by themselves incapable of justifying moral beliefs. I argue that this is a mistake and that the position that moral beliefs are justified exclusively by non-moral beliefs—a view that I call moral inferentialism—presents an attractive non-sceptical moral epistemology.

The ‘No Ought From Is’ principle (or ‘NOFI’) states that a valid argument cannot have both an ethical conclusion and non-ethical premises. Arthur Prior proposed several well-known counterexamples, including the following: Tea-drinking is common in England; therefore, either tea-drinking is common in England or all New Zealanders ought to be shot. My aim in this paper is to defend NOFI against Prior’s counterexamples. I propose two novel interpretations of NOFI and prove that both are true.

Mere facts about how the world is cannot determine how we ought to think or behave. Elqayam & Evans (E&E) argue that this undercuts the use of rational analysis in explaining how people reason, by ourselves and with others. But this presumed application of the fallacy is itself fallacious. Rational analysis seeks to explain how people do reason, for example in laboratory experiments, not how they ought to reason. Thus, no ought is derived from an is; and (...) rational analysis is unchallenged by E&E's arguments. (shrink)

Ever since its formulation by Hume, the idea of an inferential barrier between non-ethical (“is”) propositions and ethical (“ought”) propositions (also known as Hume’s is-ought thesis) has received much philosophical attention. Prior’s Paradox appears to demonstrate that the ban on “is”-“ought” inferences is violated in every possible instance, from which it follows that Hume’s is-ought thesis must be false. In this article, I will formulate a logically rigorous version of Hume’s is-ought thesis, introduce Prior-style counterexamples, (...) and suggest how they might demonstrate the falsity of Hume’s is-ought thesis, identify the substitution criterion, and develop at length the unrestricted and restricted versions of this criterion as it is applied by Pigden and Schurz. Thereafter, I will outline Schurz’s defence of the is-ought gap in accordance with his interpretation of the substitution criterion, before introducing a more sophisticated version of Prior-style objections, proposing a possible response from Pigden, identifying the costs of Pigden’s response and counter proposing a response on behalf of Schurz through an extension of his approach, and offering concluding remarks. (shrink)

The view that ‘ought’ cannot be deduced from ‘is’, credited to Hume as a major insight into the nature of morality, is surprisingly easy to refute. What they are doing is evil. Therefore, they ought not to do it. Here we have a case of deducing ‘ought’ from ‘is’. The conclusion follows, because ‘ought not’ is analytic to ‘evil’. ‘Ah, but that's just what is wrong with the example: the premise is not a pure “is”; it (...) contains an “ought”, though this does not appear explicitly.’ This is true, of course; the inference would not be valid otherwise. Still, the example shows that the is/ought principle will not do as it stands. (shrink)

The view that ‘ought’ cannot be deduced from ‘is’, credited to Hume as a major insight into the nature of morality, is surprisingly easy to refute. What they are doing is evil. Therefore, they ought not to do it. Here we have a case of deducing ‘ought’ from ‘is’. The conclusion follows, because ‘ought not’ is analytic to ‘evil’. ‘Ah, but that's just what is wrong with the example: the premise is not a pure “is”; it (...) contains an “ought”, though this does not appear explicitly.’ This is true, of course; the inference would not be valid otherwise. Still, the example shows that the is/ought principle will not do as it stands. (shrink)

In this paper we use proof-theoretic methods, specifically sequent calculi, admissibility of cut within them and the resultant subformula property, to examine a range of philosophically-motivated deontic logics. We show that for all of those logics it is a (meta)theorem that the Special Hume Thesis holds, namely that no purely normative conclusion follows non-trivially from purely descriptive premises (nor vice versa). In addition to its interest on its own, this also illustrates one way in which proof theory sheds light on (...) philosophically substantial questions. (shrink)

This essay maintains that the logical distinction between ‘is’ and ‘ought’ does not amount to a dichotomy between the natural order and the moral, or between speculative knowledge and practical. This essay thus clarifies an important and often misunderstood aspect of the natural law theory advanced by the Grisez School. While affirming the logical distinction of ‘is’ from ‘ought’, this essay attempts to argue that the principles of the moral order have a basis in human nature insofar as (...) human nature delimits the parameters of what is fulfilling for human persons. Furthermore, it is through the experience of one’s nature that one inductively grasps by a non-inferential insight the practical principles whose integral directiveness leads one to human fulfillment. The non-practical awareness of factual data one grasps in experience and which ground such a non-inferential practical insight is distinct from and more basic than reflexive, propositional, speculative knowledge (‘speculative knowledge proper’). Thus, practical understanding supposes some non-practical knowledge, although the non-practical knowledge supposed differs from speculative knowledge as ordinarily understood. Still, while the understanding of practical principles does not presuppose speculative knowledge proper, such speculative knowledge does contribute to practical reasoning in significant ways by supplying content crucial for adequate deliberation. (shrink)

This paper is an attempt to apply the truthmaker approach, recently developed by a number of authors, to the problem of providing an adequate formulation of the is–ought gap. I begin by setting up the problem and criticizing some other accounts of how the problem should be stated; I then introduce the basic apparatus of truth-making and show how it may be extended to include both descriptive and normative truth-makers; I next consider how the gap principle should be formulated, (...) attempting to deal as systematically as possible with the ‘harmless’ counter-examples; I also consider the relationship between the gap principle and various other doctrines concerning the separation between the normative and descriptive realms; and I conclude this part of the paper with some general remarks in favor of adopting the truth-maker approach over some of the alternative approaches. The paper concludes with a formal appendix, which gives precise expression to some of claims made in the previous informal part of the paper. (shrink)

Some philosophers think that there is a gap between is and ought which necessarily makes normative enquiry a different kind of thing than empirical science. This position gains support from our ability to explicate our inferential practices in a way that makes it impermissible to move from descriptive premises to a normative conclusion. But we can also explicate them in a way that allows such moves. So there is no categorical answer as to whether there is or is not (...) a gap. The question of an is-ought gap is a practical and strategic matter rather than a logical one, and it may properly be answered in different ways for different questions or at different times. (shrink)

According to John Searle’s well-known Is-Ought Argument, it is possible to derive an ought-statement from is-statements only. This argument concerns obligations involved in institutions such as promising, and it relies on the idea that institutions can be conceptualized in terms of constitutive rules. In this paper, I argue that the structure of this argument has never been fully appreciated. Starting from my status account of constitutive rules, I reconstruct the argument and establish that it is valid. This reconstruction (...) reveals that the soundness of the argument depends on whether collective acceptance as such can generate obligations. Margaret Gilbert has argued that it can, and thus far some of her central arguments have not been addressed. The upshot is that the Is-Ought Argument deserves to be taken seriously once again. (shrink)

Examining the moral sense theories of Francis Hutcheson, David Hume, and Adam Smith from the perspective of the is-ought problem, this essay shows that the moral sense or moral sentiments in those theories alone cannot identify appropriate morals. According to one interpretation, Hume's or Smith's theory is just a description of human nature. In this case, it does not answer the question of how we ought to live. According to another interpretation, it has some normative implications. In this (...) case, it draws normative claims from human nature. Anyway, the sentiments of anger, resentment, vengeance, superiority, sympathy, and benevolence show that drawing norms from human nature is sometimes morally problematic. The changeability of the moral sense and moral sentiments in Hume's and Smith's theories supports this idea. Hutcheson's theory is morally more appropriate because it bases morality on disinterested benevolence. Yet disinterested benevolence is not enough for morality. There are no sentiments the presence of which alone makes any action moral. (shrink)

Environmental ethics in its modem classical expression by Aldo Leopold appears to fall afoul of Hume’s prohibition against deriving ought-statements from is-statements since it is presented as a logical consequence of the science of ecology. Hume’s is/ought dichotomy is reviewed in its historical theoretical context. A general formulation bridging is and ought, in Hume’s terms, meeting his own criteria for sound practical argument, is found. It is then shown that Aldo Leopold’s land ethic is expressible as a (...) special case of this general formulation. Hence Leopold’s land ethic, despite its direct passage from descriptive scientific premises to prescriptive normative conclusions, is not in violation of any logical strictures which Hume would impose upon axiological reasoning. (shrink)

In a dense and fascinating article of some ten years ago, Toomas Karmo adds his voice to the chorus of philosophers who deny the possibility of soundly deriving ‘ought’ from ‘is.’ According to Karmo, no derivation containing an ethical conclusion and only non-ethical premises can possibly be sound, where ‘sound’ describes a deductively valid derivation all of whose premises are true. He also suggests that the only valid derivations of ‘ought’ from ‘is’ will be trivial ones. His argument (...) has, to my knowledge, gone unrebutted; on the contrary, it has won recent endorsements, some philosophers evidently believing that he has finally put to rest the issue of the logical autonomy of ethics. Against that trend, I intend to rebut his argument, both by falsifying the taxonomy on which his argument relies and by offering a nontrivial and potentially sound ‘is’-‘ought’ derivation of my own. (shrink)

Environmental ethics in its modem classical expression by Aldo Leopold appears to fall afoul of Hume’s prohibition against deriving ought-statements from is-statements since it is presented as a logical consequence of the science of ecology. Hume’s is/ought dichotomy is reviewed in its historical theoretical context. A general formulation bridging is and ought, in Hume’s terms, meeting his own criteria for sound practical argument, is found. It is then shown that Aldo Leopold’s land ethic is expressible as a (...) special case of this general formulation. Hence Leopold’s land ethic, despite its direct passage from descriptive scientific premises to prescriptive normative conclusions, is not in violation of any logical strictures which Hume would impose upon axiological reasoning. (shrink)

We propose a critique ofnormativism, defined as the idea that human thinking reflects a normative system against which it should be measured and judged. We analyze the methodological problems associated with normativism, proposing that it invites the controversial “is-ought” inference, much contested in the philosophical literature. This problem is triggered when there are competing normative accounts (the arbitration problem), as empirical evidence can help arbitrate between descriptive theories, but not between normative systems. Drawing on linguistics as a model, we (...) propose that a clear distinction between normative systems and competence theories is essential, arguing that equating them invites an “is-ought” inference: to wit, supporting normative “ought” theories with empirical “is” evidence. We analyze in detail two research programmes with normativist features – Oaksford and Chater's rational analysis and Stanovich and West's individual differences approach – demonstrating how, in each case, equating norm and competence leads to an is-ought inference. Normativism triggers a host of research biases in the psychology of reasoning and decision making: focusing on untrained participants and novel problems, analyzing psychological processes in terms of their normative correlates, and neglecting philosophically significant paradigms when they do not supply clear standards for normative judgement. For example, in a dual-process framework, normativism can lead to a fallacious “ought-is” inference, in which normative responses are taken as diagnostic of analytic reasoning. We propose that little can be gained from normativism that cannot be achieved by descriptivist computational-level analysis, illustrating our position with Hypothetical Thinking Theory and the theory of the suppositional conditional. We conclude that descriptivism is a viable option, and that theories of higher mental processing would be better off freed from normative considerations. (shrink)

In a dense and fascinating article of some ten years ago, Toomas Karmo adds his voice to the chorus of philosophers who deny the possibility of soundly deriving ‘ought’ from ‘is.’ According to Karmo, no derivation containing an ethical conclusion and only non-ethical premises can possibly be sound, where ‘sound’ describes a deductively valid derivation all of whose premises are true. He also suggests that the only valid derivations of ‘ought’ from ‘is’ will be trivial ones. His argument (...) has, to my knowledge, gone unrebutted; on the contrary, it has won recent endorsements, some philosophers evidently believing that he has finally put to rest the issue of the logical autonomy of ethics. Against that trend, I intend to rebut his argument, both by falsifying the taxonomy on which his argument relies and by offering a nontrivial and potentially sound ‘is’-‘ought’ derivation of my own. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:64. ON HUME'S IS-OUGHT THESIS The famous thesis of Hume about "is" and "ought" I take to be, as I believe it has generally been taken to be: (1) For any factual statement e and any ethical statement h, h is not deducible from e. My object in these brief notes is neither to defend nor to attack (1), but just to point out certain mistakes which (...) have been made, or are apt to be made, about (1), or about what Hume's thesis is. A. Max Black has taken Hume's thesis to be that "only statements of fact can follow- from statements of facti* ¡ a thesis, Black thinks, which Popper and "many other philos c be ; osophers" believe. That is. Black took Hume's thesis to (2)For any factual e and any non-factual h, h is not deducible. from e. It is certain, however, that Popper does not believe (2), and I hope it is untrue that many other philosophers believe it. For (2) is obviously false, and on the contrary, every factual statement has at least one nonfactual consequence; since from any factual statement 'f, the statement *f or not-f, which is not factual, is deducible. But this leaves Hume's thesis (1) untouched, since there is no excuse for confusing it with the foolish thesis (2). B. If a statement h is not deducible from a statement e, then given e, the falsity of h is possible; or in other words, h has less than maximum probability in relation to e. So part at least of the content of Hume's thesis (1) is: (3)For any factual e and ethical h, P(h/e). (shrink)