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Pascal, Blaise (1623-1662)

French mathematician and theologian. A member of the community at Port-Royal, Pascal in the Lettres provinciales (Provincial Letters) (1657) defended his Jansenist friends against the persecution of the Jesuits. In Les Pensées (Thoughts) (1665), Pascal defended a fideistic approach to religion, according to which "Le coeur a ses raisons que la raison ne connaît point." ("The heart has its reasons that reason does not know at all.") Pascal's work with Fermat on the nature of probability presaged the development of modern decision theory, on the basis of which he argued that belief in god, although not rational, is a clever wager.

Recommended Reading: Ben Rogers, Pascal (Routledge, 1999); Dawn M. Ludwin, Blaise Pascal's Quest for the Ineffable (Peter Lang, 2001); Leszek Kolakowski, God Owes Us Nothing: A Brief Remark on Pascal's Religion and on the Spirit of Jansenism (Chicago, 1998); and Buford Norman, Portraits of Thought: Knowledge, Methods, and Styles in Pascal (Ohio State, 1989).

Also see SEP on Pascal and the wager, virtuSens, CE, David Wilkins, MMT, EB, WSB, ELC, and Robert Sarkissian.


Literally, "rule by the father;" hence, any social or political system that grants privileged status to males and permits or encourages their domination of females. Most Western cultures have been, and continue to be, patriarchal in this sense.

Recommended Reading: Sandra Lee Bartky, Femininity and Domination: Studies in the Phenomenology of Oppression (Routledge, 1991); Gerda Lerner, The Creation of Patriarchy (Oxford, 1987); Frances B. O'Connor and Becky S. Drury, The Female Face in Patriarchy: Oppression As Culture (Michigan State, 1998); Carole Pateman, The Disorder of Women: Democracy Feminism and Political Theory (Stanford, 1990); and After Patriarchy: Feminist Transformations of the World Religions, ed. by William R. Eakin, Jay B. McDaniel, and Paula Cooey (Orbis, 1991).

Also see SEP and EB.

Peano, Giuseppe (1858-1932)

Italian mathematician and logician who formalized Dedekind's insight that the arithmetic of natural numbers could be constructed as an axiomatic system. In Arithmetices principia nova methodo exposita (The principles of arithmetic, presented by a new method) (1889) Peano showed how to derive all of arithmetic from the principles of logic, together with a set of nine postulates about numbers:

  1. 1 is a number.
  2. Every number is equal to itself.
  3. Numerical equality is commutative.
  4. Numbers both equal to a third are equal to each other.
  5. Anything equal to a number is a number.
  6. The successor of any number is a number.
  7. No two distinct numbers have the same successor.
  8. 1 is not the successor of any number.
  9. Any property that is: (a) true of 0, and (b) if true of any number is true of its successor, must be true of all numbers.
This foundation for mathematical induction was an important step toward the twentieth-century logicization of arithmetic.

Recommended Reading: Selected works of Giuseppe Peano (Toronto, 1973); Hubert Kennedy, Peano: Life and Work of Guiseppe Peano (Kluwer, 1980); and D. A. Gillies, Frege, Dedekind, and Peano on the Foundation of Arithmetic (Van Gorcum, 1988).

Also see WSB, MMT, and EB.

Peirce, Charles Sanders (1839-1914)

American philosopher who conceived of pragmatism as a method of inquiry designed to achieve clarity and (eventually) convergence of all opinion on an inter-subjective truth.

For a discussion of his life and works, see Peirce.


Awareness of an object of thought, especially that of apparently external objects through use of the senses. Since things don't always turn out actually to be as they seem to us, there is ample reason to wonder about the epistemological reliability of sense perception, and theories of perception offer a variety of responses. The skeptical challenge to direct realism is often answered by representative realism, phenomenalism, or idealism.

Recommended Reading: Howard Robinson, Perception (Routldege, 2001); John Foster, The Nature of Perception (Oxford, 2000); R. J. Hirst, Problems of Perception (Prometheus, 1992); Michael Swanston and Nicolas J. Wade, Visual Perception: An Introduction (Routledge, 2001); Fred I. Dretske, Perception, Knowledge and Belief (Cambridge, 2000); and Maurice Merleau-Ponty, Phenomenology of Perception (Routledge, 1992).

Also see SEP on problems with perception and its role in epistemology, IEP, DPM, and EB.

perceptual illusion

Cases in which what we apprehend by sensation does not correspond with the way things really are. Thus, for example, the apparent discontinuity between the portions of a spoon in and out of a glass of water is a visual illusion caused by the different indices of refraction of water and air. Representationalists commonly try to account for such cases by appeal to the distinction between primary and secondary qualities, but skeptics and idealists use perceptual illusion to raise more general doubts about the reliability of sensory knowledge.

Recommended Reading: John W. Yolton, Perception & Reality: A History from Descartes to Kant (Cornell, 1996); William P. Alston, The Reliability of Sense Perception (Cornell, 1996); and Mark B. Fineman, The Nature of Visual Illusion (Dover, 1996).

Also see SEP and M. G. F. Martin.


The Enlightenment belief that proper employment of reason will result in the full achievement of human potential. To various degrees, this optimistic supposition was held by Godwin, Rousseau, Saint-Simon, Kant, Hegel, Comte, and Marx.

Recommended Reading: John Arthur Passmore, The Perfectibility of Man (Liberty Fund, 2000) and Virginia L. Muller, The Idea of Perfectibility (Univ. Pr. of Am., 1986).

Also see SEP.

performative utterance

A linguistic expression used to do something. When spoken by someone in an appropriate position: "I'm sorry." makes an apology; "Play ball!" begins a baseball game; and "I now declare you husband and wife." performs a marriage. Thus, performatives are important instances of what Austin later called illocutionary acts.

Recommended Reading: J. L. Austin, How to Do Things With Words, ed. by Marina Sbisa and J. O. Urmson (Harvard, 1975) and John R. Searle, Speech Acts (Cambridge, 1970).


Greek philosophers who followed the principles of Aristotle, so-named because they learned from the master while strolling about {Gk. περιπατεω [peripateô]} in the covered walkways of the Lyceum.

Also see IEP.

perlocutionary act

The speech act of having an effect on those who hear a meaningful utterance. By telling a ghost story late at night, for example, one may accomplish the cruel perlocutionary act of frightening a child.

Recommended Reading: J. L. Austin, Philosophical Papers, ed. by Geoffrey J. Warnock and J. O. Urmson (Oxford, 1990) and A Companion to the Philosophy of Language, ed. by Crispin Wright and Bob Hale (Blackwell, 1999).

Perry, Ralph Barton (1876-1957)

American philosopher; author of a prize-winning biography of William James, The Thought and Character of William James. Perry participated in the early twentieth-century movement toward perceptual realism, arguing against the idealistic identification of knower and known in "The Ego-Centric Predicament" (1910) In The General Theory of Value (1926) and Realms of Value (1954) Perry defended a naturalistic definition of value in terms of subjective interest. Puritanism and Democracy (1944) is a popular exposition of American intellectual principles. Perry's articles on Philosophy generally and The Rise of Modern Philosophy contributed to the academic interpretation of The Harvard Classics.

Also see EB.

per se / per accidens

Latin phrases meaning "through itself" and "by accident," used by medieval philosophers to distinguish essential and accidental features of substances.


An individual capable of moral agency. Although the details of their theories of human nature differ widely, Descartes, Locke, Kant, and Strawson all accepted a functional description of the person that includes both mental and physical features: the attribution of responsibility to a moral agent requires both the ability to choose and an ability to act on that choice.

Recommended Reading: James B. Reichmann, Philosophy of the Human Person (Loyola, 1985); P. F. Strawson, Individuals: an Essay in Descriptive Metaphysics (Routledge, 1979); Roderick M. Chisholm, Person and Object: A Metaphysical Study (Open Court, 1979); Derek Parfit, Reasons and Persons (Oxford, 1986); Richard Moran, Authority and Estrangement (Princeton, 2001); A.J. Ayer, Concept of a Person (Palgrave, 1998); and Phyllis Sutton, Sartre's Concept of a Person: An Analytic Approach (Massachusetts, 1976).

Also see IEP, SEP on biological and feminist theories, and Amos Yong.

personal identity

The persistent identity of persons is a matter of special concern for both moral decision-making and the imposition of moral sanctions that are fair and effective. Under what criteria may we be sure of the identity of the moral agent at different times? Locke proposed a theory of personal identity based on self-conscious appropriation of past and future events. More recently, many philosophers have pointed out the difficulty of establishing the identity of persons independently of their bodily continuity.

Recommended Reading: Personal Identity, ed. by John Perry (California, 1975); John R. Perry, A Dialogue on Personal Identity and Immortality (Hackett, 1978); John A. Reuscher, Essays on the Metaphysical Foundation of Personal Identity (Univ. Pr. of Am., 1981); John Perry, Identity, Personal Identity and the Self (Hackett, 2002); and David H. Lund, Perception, Mind and Personal Identity (Univ. Pr. of Am., 1994).

Also see SEP, EB, and Daniel E. Palmer.

persuasive definition

An effort to influence attitudes by surreptitiously attaching emotive significance to the meaning of a term. According to Stevenson, the most common instance is an effort to change the descriptive meaning of an emotionally-charged evaluative term.


Belief that things generally happen for the worst {Lat. pessimus}; the opposite of optimism. Thus, for example, Schopenhauer was a pessimist who supposed that life is endless suffering.

Recommended Reading: Arthur Schopenhauer, The Essays of Schopenhauer: Studies in Pessimism (De Young, 1997); Miguel De Unamuno, Tragic Sense of Life, tr. by J. Crawford Flitch (Dover, 1990); and Raymond Tallis, Enemies of Hope: A Critique of Contemporary Pessimism (Palgrave, 1999).

Also see ISM and PP.

petitio principii

The fallacy of circular reasoning; see begging the question.


Belief that the immediate objects of sensation provide no evidence for the existence of anything beyond themselves. Taken together with basic principles of empiricism, this entails that what we usually describe as physical objects have no reality apart from our individual, private perceptual experiences of them. Although an anticipation of this view may occur in the work of Berkeley, Mill and most of the logical positivists explicitly defended some form of phenomenalism.

Recommended Reading: Richard A. Fumerton, Metaphysical and Epistemological Problems of Perception (Nebraska, 1981); Thomas Metzinger, Conscious Experience (Imprint Academic, 1996); Michael Tye, Ten Problems of Consciousness (Bradford, 1995); and J. W. Cornman, Perception, Common Sense, and Science (Yale, 1984).

Also see IEP, SEP, EB, DPM, and ISM.


Description of experience. Hence, a philosophical method restricted to careful analysis of the intellectual processes of which we are introspectively aware, without making any assumptions about their supposed causal connections to existent external objects. Philosophers who have made extensive use of diverse phenomenological methods include Brentano, Husserl, Hartmann, Heidegger, and Merleau-Ponty.

Recommended Reading: Robert Sokolowski, Introduction to Phenomenology (Cambridge, 2000); The Phenomenology Reader, ed. by Dermot Moran and Tim Mooney (Routledge, 2001); Dermot Moran, Introduction to Phenomenology (Routledge, 2000); Edmund Husserl, Crisis of European Sciences and Transcendental Phenomenology: An Introduction to Phenomenological Philosophy, tr. by David Carr (Northwestern, 1970); The Essential Husserl: Basic Writings in Transcendental Phenomenology, ed. by Donn Welton (Indiana, 1999); and Maurice Merleau-Ponty, Husserl at the Limits of Phenomenology, tr. by Lawrence Lawlor (Northwestern, 2001).

Also see SEP, IEP, EB, and DPM.

phenomena / noumena

Kant's distinction between things as they appear to us and things as they are in themselves {Ger. Ding an sich}. Although cautious application of transcendental arguments may provide a firm basis for knowledge of the former, Kant supposed, the latter lie forever beyond our grasp.

Recommended Reading: Immanuel Kant, Critique of Pure Reason, ed. by Paul Guyer and Allen W. Wood (Cambridge, 1999).

Also see IEP and EB.


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