Reasons transmit. If one has a reason to attain an end, then one has a reason to effect means for that end: reasons are transmitted from end to means. I argue that the likelihood ratio (LR) is a compelling measure of reason transmission from ends to means. The LR measure is superior to other measures, can be used to construct a condition specifying precisely when reasons transmit, and satisfies intuitions regarding end-means reason transmission in a broad array of cases.
KeywordsInstrumental rationality Reason transmission Means-end reasoning Likelihood ratio Probability
Niko Kolodny first introduced to me to a principle of reason transmission during his colloquium talk at University of California, San Diego (2009); I have since benefited from detailed correspondence with Kolodny. Nancy Cartwright gave meticulous feedback on an earlier version of this paper, and I am grateful for support from the Social Sciences and Humanities Research Council of Canada.
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