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Indiana University Bloomington

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Mark Kaplan

Mark KaplanProfessor of Philosophy

Office: Sycamore Hall 113
Phone: 855-2539
Email: kaplanm at

Curriculum Vitae PDF


  • Brown University, B.A. 1973
  • University of Michigan, M.A. 1976, Ph.D. 1978

In 1926, the Cambridge philosopher and mathematician Frank P. Ramsey wrote a paper, "Truth and Probability," in which he made two startling claims. He claimed that (a) if they are to be consistent, a person's degrees of belief in propositions (which measure how confident she is in the truth of the propositions) must obey the probability calculus; and (b) one can establish as much by an argument that appeals to nothing but principles that specify conditions under which a person's preferences count as rational. Some thirty years later, these two claims became the foundation stones for Bayesian decision theory . One focus of my research has been to assess what there is for an epistemologist to learn from Bayesian decision theory. My contention is that, suitably formulated, Ramsey's claims constitute essential contributions to epistemology-including epistemology as we ordinarily think of it: the study of justified belief and knowledge. I argued as much in my book, Decision Theory as Philosophy (Cambridge 1996). And I continue to work out the epistemological import of Ramsey's ideas for contemporary epistemology.

But my attention has been increasingly drawn to another paper, this one written by an Oxford philosopher and published in 1946: J. L. Austin's "Other Minds." Austin, a force in Oxford for the fifteen years after the end of the Second World War, was the leading exponent of what was called 'ordinary language philosophy'. "Other Minds" was his first published foray into epistemology. What is distinctive about Austin's approach to epistemology (and earns it the 'ordinary language' moniker) is the way he thought an epistemological thesis is to be tested-by assessing how faithful that thesis is to our ordinary practices: to what we say and do, and think right to say and do, in ordinary life. It is an approach to epistemology that has long been thought to be open to fatal objections. But properly understood, I contend, not only is his approach not open to these objections, the approach provides the key to making real progress in epistemology. Thus my new project (already well underway): to rehabilitate the reputation of Austin's epistemological writings. I am arguing that Austin has vital contributions to offer to contemporary debates about skepticism and, more generally, the nature and extent of knowledge and justified belief.