MECHANISM is the general name for a theory which holds that natural phenomena can be and should be explained by reference to matter and motion and their laws. The term, how ever, is used in rather different senses in different contexts, ac cording to the nature of the other view which it is intended to contradict. The principal antitheses are these: Mechanism versus Super-naturalism; Mechanism versus Teleology; Mech anism versus Vitalism ; Mechanism versus Emergence. The enumeration follows more or less the historical order of the con troversies which each pair of antithetic terms suggests. In the 17th century a great deal was written in favour of the "me chanical philosophy." "The tenets of mechanical philosophy," as Robert Boyle conceived it, consisted in explaining the physical phenomena of nature by means of "little bodies variously fig ured and moved." What the upholders of the "mechanical philosophy" were most concerned about was the elimination from science of such notions as "substantial forms," '"occult. qualities," "hypostatical principles," etc., which had long ob structed the path of natural knowledge. Boyle himself did not see any inconsistency in combining "mechanical" with teleologi cal explanations or with the assumption that Nature has "de signs." Spinoza, on the other hand, regarded the mechanical method of explanation as incompatible with the teleological and the supernatural. In view of the once prevalent proneness to explain natural phenomena teleologically, and teleologically only (which Voltaire still found it necessary to ridicule) the support ers of a mechanical, anti-teleological attitude in science no doubt rendered an important service. But the subsequent development
of the biological sciences tended to show the inadequacy of a merely mechanical explanation of vital phenomena. While admit ting the need of pursuing mechanical modes of explanation as far as possible, it has been felt with increasing urgency that something more is required to account for the facts of life than the laws of matter and motion. The opposition to biological mechanism, or mechanical biology, first took the form of what is known as Vitalism or the assumption that there is in each living organism a kind of entelechy (q.v.) or directive vital principle. This kind of vitalism was especially vindicated by H. Driesch. More recently Lloyd Morgan and others have advocated a theory of emergence (q.v.) in opposition not only to biological mecha nism, but to the theory of exclusive mechanism even in chemistry and other physical sciences. In its application to biology, the doctrine of emergence has been called emergent vitalism in con trast to the vitalism of Driesch which is called substantial vitalism. See EMERGENCE EVOLUTION AND MIND.