Bastiaan Cornelis van Fraassen (/vænˈfrɑːsən/;Dutch:[vɑnˈfraːsə(n)]; born 5 April 1941) is aDutch-American philosopher noted for his contributions tophilosophy of science,epistemology andformal logic. He is aDistinguished Professor ofPhilosophy atSan Francisco State University and the McCosh Professor of PhilosophyEmeritus atPrinceton University.

Van Fraassen was born in theGerman-occupied Netherlands on 5 April 1941. His father, asteam fitter, was forced by the Nazis to work in a factory inHamburg. After the war, the family reunited and, in 1956, emigrated toEdmonton, in westernCanada.^[6]

Van Fraassen earned hisB.A. (1963) from theUniversity of Alberta and hisM.A. (1964) andPh.D. (1966, under the direction ofAdolf Grünbaum) from theUniversity of Pittsburgh. He previously taught atYale University, theUniversity of Southern California, theUniversity of Toronto and, from 1982 to 2008, atPrinceton University, where he is now emeritus.^[7] Since 2008, van Fraassen has taught atSan Francisco State University, where he teaches courses in thephilosophy of science,philosophical logic, andthe role of modeling in scientific practice.^[8][9]

Van Fraassen is an adult convert to theRoman Catholic Church^[10] and is one of the founders of theKira Institute. He is a fellow of the American Academy of Arts and Sciences; an overseas member of theRoyal Netherlands Academy of Arts and Sciences since 1995;^[11] and a member of theInternational Academy of Philosophy of Science.^[12] In 1986, van Fraassen received theLakatos Award for his contributions to the philosophy of science and, in 2012, thePhilosophy of Science Association's inaugural Hempel Award for lifetime achievement in philosophy of science.^[13]

Among his many students are the philosophersElisabeth Lloyd atIndiana University, Anja Jauernig atNew York University, Jenann Ismael at Johns Hopkins University, Ned Hall at Harvard University, Alan Hajek at the Australian National University and Professor of Mathematics Jukka Keranen atUCLA.

Van Fraassen coined the term "constructive empiricism" in his 1980 bookThe Scientific Image, in which he argued for agnosticism about the reality of unobservable entities. That book was "widely credited with rehabilitating scientificanti-realism."^[14] According to theStanford Encyclopedia of Philosophy:

The constructive empiricist follows thelogical positivists in rejecting metaphysical commitments in science, but parts with them regarding their endorsement of the verificationist criterion of meaning, as well as their endorsement of the suggestion that theory-laden discourse can and should be removed from science. Before van Fraassen'sThe Scientific Image, some philosophers had viewed scientificanti-realism as dead, because logical positivism was dead. Van Fraassen showed that there were other ways to be an empiricist with respect to science, without following in the footsteps of the logical positivists.^[14]

Paul M. Churchland, one of van Fraassen's critics, contrasted van Fraassen's idea of unobservable phenomena with the idea of merelyunobserved phenomena.^[15]

In his 1989 bookLaws and Symmetry, van Fraassen attempted to lay the ground-work for explaining physicalphenomena without assuming that such phenomena are caused by rules or laws which can be said to cause or govern their behavior. Focusing on the problem ofunderdetermination, he argued for the possibility that theories could have empirical equivalence but differ in theirontological commitments. He rejects the notion that the aim of science is to produce an account of the physical world that is literally true and instead maintains that its aim is to produce theories that are empirically adequate.^[16] Van Fraassen has also studied thephilosophy of quantum mechanics, philosophical logic, andBayesian epistemology.

Van Fraassen has been the editor of theJournal of Philosophical Logic and co-editor of theJournal of Symbolic Logic.^[7]

In logic, Van Frassen is best known for his work onfree logic and his introduction of thesupervaluationsemantics. In his paper "Singular Terms, Truth-value Gaps, and Free Logic",^[17] van Fraassen opens with a very brief introduction of the problem ofnon-referring names.

Instead of any unique formalization, though, he simply adjusts the axioms of a standard predicate logic such as that found inWillard Van Orman Quine'sMethods of Logic. Instead of an axiom like${\displaystyle \mathrm{\forall }xPx\Rightarrow \mathrm{\exists }xPx}$ he uses${\displaystyle (\mathrm{\forall }xPx\wedge \mathrm{\exists }x(x=a))\Rightarrow \mathrm{\exists }xPx}$; this will naturally be true if the existential claim of the antecedent is false. If a name fails to refer, then the atomic sentence containing it can be assigned a truth value arbitrarily, provided that it is not an identity statement. Free logic is proved to be complete under this interpretation.

He indicates that, however, he sees no good reason to call statements which employ them either true or false. Some have attempted to solve this problem by means ofmany-valued logics; van Fraassen offers in their stead the use ofsupervaluations. Questions of completeness change when supervaluations are admitted, since they allow for valid arguments that do not correspond to logically true conditionals.

His paper "Facts and tautological entailment" (J Phil 1969) is now regarded as the beginning of truth-maker semantics.

In "Belief and the Will", van Fraassen proposed what is now known asvan Fraassen's reflection principle: "to satisfy the principle, the agent's present subjective probability for propositionA, on the supposition that his subjective probability for this proposition will equalr at some later time, must equal this same numberr".^[18] WithinBayesian epistemology this principle is recognized as an importantsynchronic norm; however van Fraassen points out that aDutch Book argument can be made against the principle.^[19][20]

• Scientific Representation: Paradoxes of Perspective, OUP, 2008.
• The Empirical Stance, Yale University Press, 2002.
• Quantum Mechanics: An Empiricist View, Oxford University Press, 1991.
• Laws and Symmetry, Oxford University Press 1989.
• The Scientific Image, Oxford University Press 1980.
• Derivation and Counterexample: An Introduction to Philosophical Logic (with Karel Lambert), Dickenson Publishing Company, Inc. 1972.
• Formal Semantics and Logic, Macmillan, New York 1971.
• An Introduction to the Philosophy of Time and Space, Random House, New York 1970.

• American philosophy
• List of American philosophers

Wikiquote has quotations related toBas van Fraassen.

• van Fraassen's homepage at Princeton.
• van Fraassen's faculty page (2009) at the Department of Philosophy, San Francisco State University.

• 1941 births
• Living people
• 20th-century American male writers
• 20th-century American non-fiction writers
• 20th-century American philosophers
• 20th-century Dutch male writers
• 20th-century Dutch non-fiction writers
• 20th-century Dutch philosophers
• 20th-century Roman Catholics
• 21st-century American male writers
• 21st-century American non-fiction writers
• 21st-century American philosophers
• 21st-century Dutch male writers
• 21st-century Dutch non-fiction writers
• 21st-century Dutch philosophers
• 21st-century Roman Catholics
• Academic staff of the University of Toronto
• American epistemologists
• American logicians
• American male non-fiction writers
• American philosophy academics
• American Roman Catholic writers
• Analytic philosophers
• Catholic philosophers
• Converts to Roman Catholicism
• Corresponding fellows of the British Academy
• Dutch logicians
• Dutch male non-fiction writers
• Dutch Roman Catholic writers
• Lakatos Award winners
• Members of the Royal Netherlands Academy of Arts and Sciences
• People from Goes
• Philosophers of physics
• Philosophers of time
• Princeton University faculty
• San Francisco State University faculty
• University of Alberta alumni
• University of Pittsburgh alumni
• University of Southern California faculty
• Yale University faculty

• Webarchive template wayback links
• Articles with short description
• Short description is different from Wikidata
• Articles with hCards
• Pages with Dutch IPA