Dialogical Logic Dialogical logic is an approach to logic in which the meaning of the logical constants (connectives and quantifiers) and the notion of validity are explained in game-theoretic terms. The meaning of each logical constant (such as “and”, “or”, “implies”, “not”, “every”, and so forth) is given in terms of how assertions containing these logical constants can be attacked and defended in an adversarial dialogue. Dialogues are described as two-player

Persistence in Time No person ever steps into the same river twice—or so goes the Heraclitean maxim. Obscure as it is, the maxim is often taken to express two ideas. The first is that everything always changes, and nothing remains perfectly similar to how it was just one instant before. The second is that nothing survives this constant flux of change. Where there appears to

Ikhwan al-Safa’ Ikhwān al-safā’ (the Brethren of Purity) are the authors of the Rasā’il al-Ikhwān al-safā’ (Treatises of the Brethren of Purity), an Islamic encyclopedia consisting of fifty-two treatises and an additional comprehensive treatise (Risālat al-jāmi‘a) on various philosophical sciences interpreted by Ismā‘īlī Shī‘ī scholars. It covers the mathematical, natural, psychological/rational, and theological sciences and was written in the tenth or eleventh century C.E. The

Samuel Alexander (1859—1938) Samuel Alexander is best known for his role in British Emergentism, an early twentieth century movement which uses the notion of emergence to explain the relationship between mind and body. Alexander argues that mind emerges from body, in the sense that mind is dependent upon brain but not reducible to it. Alexander is also variously associated with both of the major competing

Egoism In philosophy, egoism is the theory that one’s self is, or should be, the motivation and the goal of one’s own action. Egoism has two variants, descriptive or normative. The descriptive (or positive) variant conceives egoism as a factual description of human affairs. That is, people are motivated by their own interests and desires, and they cannot be described otherwise. The normative variant proposes