224 THEORY OF KNOWLEDGE. cause and effect. Whence, then, do we obtain the knowledge of cause and effect? Not by «/rwr/ thought. Pure reason is able only to analyze concepts into their elements, not to connect new predicates with them. All its judgments are analytic, while synthetic judgments rest on experience. Judgments concerning causation belong in this latter class, for effects are entirely distinct from causes; the effect is not contained in the cause, nor the latter in the former. In the case of a phenomenon previously unknown we cannot tell from what causes it has proceeded, nor what its effect will be. We argue that fire will warm us, and bread afford nourishment, because we have often perceived these causal pairs closely connected in space and time. But even experi- ence does not vouchsafe all that we desire. It shows nothing more than the coexistence and succession of phe- nomena and events; while the judgment itself, ^. ^., that the motion of one body stands in causal connection with that of another, asserts more than mere contiguity in space and time, it affirms not merely that the one precedes the other, but that it produces it — not merely that the second follows the first, but that it results from it. The bond which connects the two events, the force that puts forth the second from the first, the necessary connection between the two is not perceived, but added to perception by thought, con- strued into it.* What, then, is the occasion and what the warrant for transforming perceived succession in time into causal succession, for substituting must for is, for interpret- ing the observed connection of fact into a necessary connec- tion which always eludes observation? We do not causally connect every chance pair of succes- sive events, but those only which have been repeatedly observed together. The wonder is, then, that through oft- repeated observation of certain objects we come to believe that we know something about the behavior of other like objects, and the further behavior of these same ones. From the fact that I have seen a given apple fall ten times to the
- The weakness of the concept of cause had been recognized before Hume
by the skeptic, J. Glanvil (1636-80). Causality itself cannot be perceived ; we infer it from the constant succession of two phenomena, without being able to j show warrant for the transformation of thereafter into thereby.
