Mr. Peirce objects to necessitarianism, and classes it together with materialism and the mechanical philosophy, speaking of the latter as the most logical form of necessitarianism. In consonance with the dictionary-definitions of these words, he contrasts them to the doctrine of the freedom of the will and also to miracles—the latter, we must confess, being a dangerous concession to certain theological conceptions. The “Century Dictionary” defines “necessitarianism” as “The theory that the will is subject to the general mechanical law of cause and effect.” And “necessitarian” as “One who maintains the doctrine of philosophical necessity, in opposition to that of the freedom of the will: opposed to libertarian.” The word “determinism” is regarded as a synonym of necessitarianism. Its first definition in the “Century Dictionary” reads as follows: “A term invented by Sir William Hamilton to denote the doctrine of the necessitarian philosophers, who hold that man’s actions are uniformly determined by motives acting upon his character, and that he has not the power to choose to act in one way so long as he prefers on the whole to act in another way.” Hamilton’s definition as here presented is puzzling. If the words “choose” and “prefer on the whole” are _not_ meant to be tautological, there is no sense in it; for no determinist denies that a man might “upon the whole” prefer to act this way, while he has the power to choose, and for special considerations perhaps does choose, to act in another way. However, if the words “choose” and “prefer on the whole” are meant to be tautological, the self-contradictoriness of the statement is too palpable for a Hamilton. Is there anybody who would maintain that a man who chooses to act in one way can at the same time, under the very same circumstances, and he remaining the very same man of the same character and intentions, choose to act in another way? While we accept determinism and also necessitarianism in the sense that all events (the actions of willing beings included) are determined, we cannot accept either the mechanical philosophy or materialism as the terms are commonly understood. We find materialism defined as “The metaphysical doctrine that matter is the only substance, and that matter and its motions constitute the universe.” (“Century Dictionary,” 2d sense.) The mechanical philosophy is explained _sub voce_ “atomic” as “[The view that] from the diverse combination and motions of ... atoms all things, including the soul, were supposed to arise.” _Ibid._ Determinism is simply the negation of absolute chance. It does not exclude chance in the original sense of the word as an unexpected event, as something that befalls one without his seeking it or making the event—chance being derived from ML. _cadentia_, i. e. the falling, as in a throw of dice. The “Century Dictionary” defines “chance” in sense 9, as