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Conditional Obligation and Detachment*

Published online by Cambridge University Press:  01 January 2020

Mark I. Vorobej
Mark I. Vorobej*
Affiliation:
Department of Philosophy, McMaster University, Hamilton, OntarioL8S 4K1
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Extract

Suppose that John has a moral obligation to stop smoking given that smoking is dangerous to his health. Suppose further that smoking is dangerous to his health. Does it follow that John has a moral obligation to stop smoking? Although intuition inclines one to answer in the affirmative, recent developments in deontic logic apparently call this inference into question. The issue at hand is whether unconditional obligations are detachable from conditional obligations on the basis of purely factual considerations. I believe that they are not. In the course of arguing for this position I defend a novel restricted rule of detachment which is constructed out of both factual and normative components.

Type
Research Article
Information
Canadian Journal of Philosophy , Volume 16 , Issue 1 , March 1986 , pp. 11 - 26
Copyright
Copyright © The Authors 1986

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References

1 Chisholm, Roderick ‘Contrary to Duty Imperatives and Deontic Logic,’ Analysis 24 (1963) 33–6CrossRefGoogle Scholar

2 See Castañeda, Hector-Neri ‘On the Semantics of the Ought to Do,’ Synthese 21 (1970) 449–68CrossRefGoogle Scholar for a recent account of the ought to be/ought to do distinction. A fuller historical discussion can be found in Hund, William B. ‘The Distinction Between Ought to Be and Ought to Do,’ The New Scholasticism 41 (1967) 345–55.CrossRefGoogle Scholar

3 These conditions are stipulated by Aqvist, Lennart ‘Good Samaritans, Contrary to Duty Imperatives, and Epistemic Obligations,’ Nous 1 (1967) 361–79.CrossRefGoogle Scholar

4 The arguments for this are clearly outlined by DeCew, Judith Wagner ‘Conditional Obligation and Counterfactuals,’ journal of Philosophical Logic 10 (1981) 55–72.CrossRefGoogle Scholar

5 Aqvist, 366. It should be mentioned that Åqvist as well as some of those mentioned below discuss only a related robbery version of Chisholm's paradox.

6 Mott, Peter ‘On Chisholm's Paradox,’ Journal of Philosophical Logic 2 (1973) 197–211.CrossRefGoogle Scholar al-Hibri, Azizah Deontic Logic (Washington, DC: University Press of America 1978), 97Google Scholar

7 DeCew, 63

8 Tomberlin, James E. ‘Contrary to Duty Imperatives and Conditional Obligation,’ Nous 15 (1981) 357–75CrossRefGoogle Scholar. Tomberlin actually denies that even the independence requirement represents an adequacy condition.

9 All of the detachment rules discussed in this paper are meant to be truth preserving and thus could be formulated as truth-functional conditionals. However, for reasons of perspicuity, I prefer this type of graphic display.

10 DeCew, 61. A related objection to (UD) is raised by Fraassen, Bas van ‘The Logic of Conditional Obligation,’ Journal of Philosophical Logic 1 (1972) 422Google Scholar, in a discussion of the John and Suzy paradox. Van Fraassen's argument is effectively countered by al-Hibri, 73-6.

11 A recent notable exception is Lennart Åqvist and Jaap Hoepelman, ‘Some Theorems About a “Tree” System of Deontic Logic,’ in Hilpinen, Risto ed., New Studies in Deontic Logic (Boston: D. Reidel 1981) 187–221.CrossRefGoogle Scholar See also Barry Loewer and Belzer, Marvin ‘Dyadic Deontic Detachment,’ Synthese 54 (1983) 295–318.Google Scholar

12 However, see the last paragraph of section IV.

13 Fraassen, Van DeCew. David Lewis, Counterfactuals (Cambridge, MA: Harvard University Press 1973).Google Scholar

14 Thomason, Richmond ‘Deontic Logic as Founded on Tense Logic,’ in Hilpinen, 165–76.Google Scholar

15 Greenspan, Patricia ‘Conditional Oughts and Hypothetical Imperatives,’ The Journal of Philosophy 72 (1975) 259–76CrossRefGoogle Scholar

16 This inference is also endorsed by Castaneda, Hector-Neri ‘Ought, Time, and the Deontic Paradoxes,’ The Journal of Philosophy 74 (1977) 784.CrossRefGoogle Scholar

17 Conditional obligations lack this constraining power and do not directly influence action in the same way.

18 See Hansson, Bengt ‘An Analysis of Some Deontic Logics,’ Nous 3 (1969) 384.CrossRefGoogle Scholar

19 The satisfaction of this obligation is not always possible if moral dilemmas exist.

20 There is no way of expressing this obligation in the language of standard deontic logic which both prohibits iterated deontic expressions and lacks a quantificational structure. The closest approximation to it in certain enriched systems of propositional deontic logic is the widely accepted schema O(OA→A).

21 A standard definition allows us to replace the third antecedent clause -0-B of (RD) by the sentence PB which expresses B's permissibility. I prefer not to make this substitution for two reasons. First, the claim that -0-B and PB are equivalent can and has been disputed. Second, and more importantly, what I want to emphasize in (RD) is the absence of a prohibition against B rather than a positive affirmation of B's permissibility.

22 Sobel, Jordan Howard ‘Utilitarianism and Past and Future Mistakes,’ Nous 10 (1976) 195–219.CrossRefGoogle Scholar References to opposing utilitarian positions can be found in this article.

23 A principle virtually identical to (I) is discussed by Loewer and Belzer, 302, although they make no substantive use of it in their own treatment of Chisholm's paradox.

24 On this point I disagree with Bonevac, Daniel ‘Chellas on Conditional Obligation,’ Philosophical Studies 44 (1983) 252.CrossRefGoogle Scholar

25 See Wright, Georg Henrik von ‘A New System of Deontic Logic.’ Danish Yearbook of Phílosophy 1 (1964) 173–82.Google Scholar Hansson, 393-4. Van Fraassen, 436. AlHibri, 134-41.

26 The suggestions in this paragraph are due to Steve Yablo.

27 Thomason, 165

28 Chellas, Brian ‘Conditional Obligation,’ in Stenlund, S. ed., Logical Theory and Semantic Analysis (Boston: D. Reidel 1974) 27Google Scholar

29 DeCew, 62-9, discusses some problems associated with such a semantics.