Peter D. Klein
Encyclopedia
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
and chair of the department at Rutgers University
Rutgers University
Rutgers, The State University of New Jersey , is the largest institution for higher education in New Jersey, United States. It was originally chartered as Queen's College in 1766. It is the eighth-oldest college in the United States and one of the nine Colonial colleges founded before the American...
, New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
. Peter Klein received a BA
Bachelor of Arts
A Bachelor of Arts , from the Latin artium baccalaureus, is a bachelor's degree awarded for an undergraduate course or program in either the liberal arts, the sciences, or both...
at Earlham College
Earlham College
Earlham College is a liberal arts college in Richmond, Indiana. It was founded in 1847 by Quakers and has approximately 1,200 students.The president is John David Dawson...
, and a PhD
PHD
PHD may refer to:*Ph.D., a doctorate of philosophy*Ph.D. , a 1980s British group*PHD finger, a protein sequence*PHD Mountain Software, an outdoor clothing and equipment company*PhD Docbook renderer, an XML renderer...
from Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
. He is the author of Certainty: A Refutation of Skepticism (1982) and a variety of articles and reviews addressing issues in epistemology.
Klein is widely known for his work on skepticism. His most influential work, however, is on the nature of knowledge, where he has long defended the defeasibility theory. His recent work defends infinitism
Infinitism
Infinitism is the view that knowledge may be justified by an infinite chain of reasons. It belongs to epistemology, the branch of philosophy that considers the possibility, nature, and means of knowledge.-Epistemological infinitism:...
about justification
Theory of justification
Theory of justification is a part of epistemology that attempts to understand the justification of propositions and beliefs. Epistemologists are concerned with various epistemic features of belief, which include the ideas of justification, warrant, rationality, and probability...
. On this view, to be justified in believing P is to possess a reason R1 to believe P, and a reason R2 to believe R1, and a reason R3.....and so on, ad infinitum. Justification is, so to speak, "turtles all the way down
Turtles all the way down
"Turtles all the way down" is a jocular expression of the infinite regress problem in cosmology posed by the "unmoved mover" paradox. The phrase was popularized by Stephen Hawking in 1988. The "turtle" metaphor in the anecdote represents a popular notion of a "primitive cosmological myth", viz...
." He has also recently advocated a picture of knowledge according to which one can have knowledge of p even if the justification for the belief that p is essentially based on false premises. Klein calls these "useful falsehoods".