logos (plural: logoi) (Greek, ‘word’, ‘speech’, ‘reason’), term with the following main philosophical senses. (1) Rule, principle, law. E.g., in Stoicism the logos is the divine order and in Neoplatonism the intelligible regulating forces displayed in the sensible world. The term came thus to refer, in Christianity, to the Word of God, to the instantiation of his agency in creation, and, in the New Testament, to the person of Christ. (2) Proposition, account, explanation, thesis, argument. E.g., Aristotle presents a logos from first principles. (3) Reason, reasoning, the rational faculty, abstract theory (as opposed to experience), discursive reasoning (as opposed to intuition). E.g., Plato’s Republic uses the term to refer to the intellectual part of the soul. (4) Measure, relation, proportion, ratio. E.g., Aristotle speaks of the logoi of the musical scales. (5) Value, worth. E.g., Heraclitus speaks of the man whose logos is greater than that of others. R.C.