(b. Barcelona[?], Spain, ca 1340; d. Zaragoza, Spain, 1412)
Crescas lived in Barcelona and Zaragoza, was one of the most prominent leaders of the Spanish Jewish community, and performed a number of commissions for the monarchs of Aragon. Several scholars name him as a teacher, and there are indications of a circle of students around him. Crescas wrote a Hebrew philosophical-theological work entitled Or Adonai (“Light of the Lord”), which offers an unusual constellation of position, some of them characteristic of the liberals among the medieval philosophers and others characteristic of the conservatives. Thus he is willing, on the one hand, to concede the eternity of the world and in effect sacrifices human free will to considerations of natural causality. But, on the other hand, he rejects the negative theology in vogue among the Neoplatonizing Aristotelians; denies that man’s true perfection and, ultimately, human immortality are to be gained by intellectual development; and makes goodness rather than thought the central attribute of the deity.
Of particular interest for the history of natural science is a section in which Crescas examines twentyfive propositions formulated by Maimonides (d. 1204) as a summary of medieval Aristotelian physics and metaphysics. Crescas subjects these propositions to a most exacting analysis and rejects several of the most fundamental. Since at least the physical principles listed by Maimonides were genuinely Aristotelian and since it is especially against them that Crescas directs his criticism, he is in fact attacking much of the foundation of Aristotle’s physics. He answers Aristotle’s proofs of the impossibility of an infinite magnitude, an infinite place, or a vacuum. He rejects Aristotle’s definition of time; his definition of place; the theory that two elements, fire and air, are endowed with an absolute lightness that causes them to rise; and the theory that all four physical elements have their proper, natural place that is the cause of their natural motion. The drift of Crescas’ critique is toward a conception of infinite space, with the possibility of infinite worlds, and the uniformity of nature.
The argumentation used by Crescas, as well as the physical theories he advocates in opposition to Aristotle, could have been drawn from his reading; theories and arguments that previously had been raised, only to be answered, are now accepted by Crescas and combined into an overall attack on Aristotelian physics. Crescas’ sources were the writings of the Jewish philosophers and the Hebrew translations of Averroes’ (Ibn Rushd) commentaries on Aristotle. He knew Aristotle only through Averroës. Recently it has been suggested that Crescas may have been influenced by fourteenth-century Scholastic writers of the Paris school, although no literary connection has been established. Crescas was used and quoted by Pico della Mirandola and also by Spinoza. His position is similar to that of Giordano Bruno.
An edition and translation of the section of the Or Adonai concerned with natural science is H. A. Wolfson, Crescas’ Critique of Aristotle (Cambridge, Mass., 1929). Wolfson’s introduction summarizes Crescas’ position, and his masterful notes reveal the sources and history of the problems that Crescas deals with.
A suggestive recent study is Shlomo Pies, Post Thomistic Scholasticism and the Theories of Hasdai Crescas (Jerusalem, 1966), in Hebrew.
Herbert A. Davidson