ABSTRACT
A prominent term in theory of knowledge since the seventeenth century, ‘a posteriori’ signifies a kind of knowledge or justification that depends on evidence, or warrant, from sensory experience. A posteriori truth is truth that cannot be known or justified independently of evidence from sensory experience, and a posteriori concepts are concepts that cannot be understood independently of reference to sensory experience. A posteriori knowledge contrasts with a priori knowledge, knowledge that does not require evidence from sensory experience. A posteriori knowledge is empirical, experiencebased knowledge, whereas a priori knowledge is non-empirical knowledge. Standard examples of a posteriori truths are the truths of ordinary perceptual experience and the natural sciences; standard examples of a priori truths are the truths of logic and mathematics. The common understanding of the distinction between a posteriori and a priori knowledge as the distinction between empirical and non-empirical knowledge comes from Kant’s Critique of Pure Reason (1781/1787). See also: A priori
Further reading Kant, I. (1781/1787) Critique of Pure Reason,
trans. N. Kemp Smith, London: Macmillan, 1963. (Classic statement of the a priori-a posteriori and analytic-synthetic distinctions; see especially the introduction, §§I-IV.)
A PRIORI
An important term in epistemology since the seventeenth century, ‘a priori’ typically connotes a kind of knowledge or justification that does not depend on evidence, or warrant, from sensory experience. Talk of a priori truth is ordinarily shorthand for talk of truth knowable or justifiable independently of evidence from sensory experience; and talk of a priori concepts is usually talk of concepts that can be understood independently of reference to sensory experience. A priori knowledge contrasts with a posteriori knowledge, knowledge requiring evidence from sensory experience. Broadly
characterized, a posteriori knowledge is empirical, experience-based knowledge, and a priori knowledge is non-empirical knowledge. Standard examples of a priori truths are the truths of mathematics, whereas standard examples of a posteriori truths are the truths of the natural sciences. See also: A posteriori
Further reading Moser, P.K. (ed.) (1987) A Priori Knowledge,
Oxford: Oxford University Press. (Contains ten of the most important recent essays on a priori knowledge and a bibliography of recent work on the topic.)
‘ABDUH, MUHAMMAD (1849-1905)
The Egyptian reformer and Muslim apologist Muhammad ‘Abduh was a pupil and friend of al-Afghani. Although deeply influenced by him, ‘Abduh was less inclined to political activism and concentrated on religious, legal and educational reform. His best-known writings are a theological treatise, Risalat al-tawhid (translated into English as The Theology of Unity), and an unfinished Qur’anic commentary, Tafsir al-manar (The Manar Commentary), on which he collaborated with Rashid Rida. One of the key themes of these works is that since modernity is based on reason, Islam must be compatible with it. But ‘Abduh’s ‘modernism’ went hand in hand with returning to an idealized past, and his ‘rationalism’ was tempered by a belief in divine transcendence which limits the scope of intellectual inquiry. In ethics as in theology, he regarded the classical debates as arid and divisive, although on the issues of free will and moral law his position was in fact similar to that of the Mu‘tazila. See also: Islamic philosophy, modern
Further reading Abduh, M. (1897) Risalat al-tawhid (The
Theology of Unity), Cairo; trans. I. Musa‘ad and K. Cragg, The Theology of Unity, London: George Allen & Unwin, 1966. (One of ‘Abduh’s major works on philosophical theology.)
ABELARD, PETER (1079-1142)
Among the many scholars who promoted the revival of learning in western Europe in the early twelfth century, Abelard stands out as a consummate logician, a formidable polemicist and a champion of the value of ancient pagan wisdom for Christian thought. Although he worked within the Aristotelian tradition, his logic deviates significantly from that of Aristotle, particularly in its emphasis on propositions and what propositions say. According to Abelard, the subject matter of logic, including universals such as genera and species, consists of linguistic expressions, not of the things these expressions talk about. However, the objective grounds for logical relationships lie in what these expressions signify, even though they cannot be said to signify any things. Abelard is, then, one of a number of medieval thinkers, often referred to in later times as ‘nominalists’, who argued against turning logic and semantics into some sort of science of the ‘real’, a kind of metaphysics. It was Abelard’s view that logic was, along with grammar and rhetoric, one of the sciences of language.
