The Fall of “Adams’ Thesis”?
 Alan Hájek
 … show all 1 hide
Rent the article at a discount
Rent now* Final gross prices may vary according to local VAT.
Get AccessAbstract
The socalled ‘Adams’ Thesis’ is often understood as the claim that the assertibility of an indicative conditional equals the corresponding conditional probability—schematically: $${({\rm AT})}\qquad\qquad\quad As(A\rightarrow B)=P({BA}),{\rm provided}\quad P(A)\neq 0.$$ The Thesis is taken by many to be a touchstone of any theorizing about indicative conditionals. Yet it is unclear exactly what the Thesis is. I suggest some precise statements of it. I then rebut a number of arguments that have been given in its favor. Finally, I offer a new argument against it. I appeal to an old triviality result of mine against ‘Stalnaker’s Thesis’ that the probability of a conditional equals the corresponding conditional probability. I showed that for all finiteranged probability functions, there are strictly more distinct values of conditional probabilities than there are distinct values of probabilities of conditionals, so they cannot all be paired up as Stalnaker’s Thesis promises. Conditional probabilities are too finegrained to coincide with probabilities of conditionals across the board. If the assertibilities of conditionals are to coincide with conditional probabilities across the board, then assertibilities must be finergrained than probabilities. I contend that this is implausible—it is surely the other way round. I generalize this argument to other interpretations of ‘As’, including ‘acceptability’ and ‘assentability’. I find it hard to see how any such figure of merit for conditionals can systematically align with the corresponding conditional probabilities.
 Adams E. (1965) The logic of conditionals. Inquiry 8: 166–197 CrossRef
 Adams E. (1975) The logic of conditionals. Reidel, Dordrecht
 Adams E. (1990) Review of Conditionals, by Frank Jackson. Philosophical Review 99(3): 433–435 CrossRef
 Adams E. (1998) A primer of probability logic. CSLI, Stanford University, Stanford California
 Appiah A. (1984) Assertion and conditionals. Cambridge University Press, Cambridge
 Bennett J. (2003) Conditionals. Oxford University Press, Oxford
 Collins, J. (1991). Belief revision. Ph.D. thesis, Princeton University.
 DeRose K. (2010) The conditionals of deliberation. Mind 119(473): 1–42 CrossRef
 Gibbard, A. (1981). Two recent theories of conditionals. In Harper et al. (Eds.) (pp. 211–247).
 Hájek A. (1989) Probabilities of conditionals—revisited. Journal of Philosophical Logic 18: 423–428 CrossRef
 Hájek A. (2003) What conditional probability could not be. Synthese 137(3): 273–323 CrossRef
 Hájek A. (2007) The reference class problem is your problem too. Synthese 156: 563–585 CrossRef
 Hájek, A. (2011). Conditional probability. In P. Bandyopadhyay & M. Forster (Eds.), Handbook for philosophy of statistics. Amsterdam: Elsevier
 Hájek, A., & Hall, N. (1994). The hypothesis of the conditional construal of conditional probability, In E. Eells & B. Skyrms (Eds.), Probability and conditionals. Cambridge: Cambridge University Press.
 Hájek, A. A poisoned dart for conditionals (MS).
 Harper, W. L., Stalnaker, R., Pearce, G. (eds) (1981) Ifs. Reidel, Dordrecht
 Jackson F. (1987) Conditionals. Blackwell, Oxford
 Jackson F. (1998) Mind, method, and conditionals. Routledge, London CrossRef
 Jackson, F. (2008). Reply to Edgington. In I. Ravenscroft (Ed.), Mind, ethics, and conditionals: themes from the philosophy of Frank Jackson. Oxford: Oxford University Press.
 Leitgeb, H. A probabilistic semantics for counterfactuals. Part A (MS).
 Lewis, D. (1976). Probabilities of conditionals and conditional probabilities. Philosophical Review, 85, 297–315 (reprinted in Harper et al.)
 Lewis D. (1986) Probabilities of conditionals and conditional probabilities II. Philosophical Review, 95: 581–589 CrossRef
 McGee V. (1989) Conditional probabilities and compounds of conditionals. Philosophical Review 98(4): 485–541 CrossRef
 Pagin, P. (2008). Assertion. In E. N. Zalta (Ed.), The Stanford encyclopedia of philosophy (Fall 2008 Edition). URL:http://plato.stanford.edu/archives/fall2008/entries/assertion/.
 Ramsey, F. P. (1965). The foundations of mathematics (and other logical essays). London: Routledge, Kegan Paul
 Skyrms B. (1980) Causal necessity. Yale University Press, New Haven
 Stalnaker, R. (1970). Probability and conditionals. Philosophy of Science 37, 64–80 (reprinted in Harper et al.)
 Williamson T. (2000) Knowledge and its limits. Oxford University Press, Oxford
 Title
 The Fall of “Adams’ Thesis”?
 Journal

Journal of Logic, Language and Information
Volume 21, Issue 2 , pp 145161
 Cover Date
 20120401
 DOI
 10.1007/s1084901291571
 Print ISSN
 09258531
 Online ISSN
 15729583
 Publisher
 Springer Netherlands
 Additional Links
 Topics
 Keywords

 Adams’ Thesis
 Assertability
 Assertibility
 Probabilities of conditionals
 Conditional probability
 Triviality results
 Authors

 Alan Hájek ^{(1)}
 Author Affiliations

 1. Research School of Social Sciences, Australian National University, Canberra, ACT, 0200, Australia