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P.D. Magnus

Demonstrative induction and the skeleton of inference

International Studies in the Philosophy of Science, 2008.

This paper addresses demonstrative theories of induction, according to which scientific inference is deductive: Apparently ampliative inferences are really deductive inferences with suppressed premises. I argue that they may succeed as descriptive accounts, and they may provide sound, practical advice, but they cannot ground the justification of scientific claims any more firmly than inference using ampliative rules.

A draft of this paper under the title 'Eliminating induction' was first posted on-line 25dec2005. Versions were presented to the Society for Exact Philosophy meeting in La Jolla, California and to the philosophy department at Southern Methodist University.

Versions available


It has been common wisdom for centuries that scientific inference cannot be deductive; if it is inference at all, it must be a distinctive kind of inductive inference. According to demonstrative theories of induction, however, important scientific inferences are not inductive in the sense of requiring ampliative inference rules at all. Rather, they are deductive inferences with sufficiently strong premises. General considerations about inferences suffice to show that there is no difference in justification between an inference construed demonstratively or ampliatively. The inductive risk may be shouldered by premises or rules, but it cannot be shirked. Demonstrative theories of induction might, nevertheless, better describe scientific practice. And there may be good methodological reasons for constructing our inferences one way rather than the other. By exploring the limits of these possible advantages, I argue that scientific inference is neither of essence deductive nor of essence inductive.


	AUTHOR = {P.D. Magnus},
	TITLE = {Demonstrative induction and the skeleton of inference},
	JOURNAL = {International Studies in the Philosophy of Science},
	YEAR = {2008},
	MONTH = oct,
	VOLUME = {22},
	NUMBER = {3},
	PAGES = {303--315}