Causality

Most of Aristotle's views were accepted by the Scholastics. Aristotle thought that the chains of efficient causes must stop at some "unmoved movers"—that is, things that are themselves unmoved but produce motion to other things. The Scholastics thought that the only proper efficient cause was God, being the ultimate unmoved mover. Later thinkers revolted against all but efficient causality. Efficient causality, what Aristotle called "the source of motion" (195a10), was taken to be the only type of causality by all those who advocated, in one form or another, the mechanical philosophy: in their hands, efficient causality became tantamount to pushings and pullings. Final causes, in particular, were cast to the winds. Where Aristotle saw goals and purposes in nature, mechanical philosophers either excised purpose from nature (Hobbes, Hume) or placed it firmly in the hands of God (Descartes, Leibniz). The moderns also revolted, to varying degrees, against the rich ontological landscape that Aristotle had painted: essences, substantial forms, activities, and so on. However, two key Aristotelian ideas, that there is necessity in nature and that this necessity is the same as the logical necessity of a demonstrative argument, were to become part of the mainstream philosophical thinking about causality until David Hume (1711–1776) subjected them to severe criticism and undermined them.