EMPIRICAL LAWS.
Empirical laws are derivative laws, of which the derivation is not
known. They are observed uniformities, which we compare with the result
of any deduction to verify it; but of which the _why_, and also the
limits, are unrevealed, through their being, though resolvable, not yet
resolved into the simpler laws. They depend usually, not solely on the
ultimate laws into which they are resolvable; but on those, together
with an ultimate fact, viz. the mode of coexistence of some of the
component elements of the universe. Hence their untrustworthiness for
scientific purposes; for, till they have been resolved (and then a
derivative law ceases to be empirical), we cannot know whether they
result from the different effects of one cause, or from effects of
different causes; that is, whether they depend on laws, or on laws and a
collocation. And if they thus depend on a collocation, they can be
received as true only within the limits of time and space, and also
circumstance, in which they have been observed, since the mode of the
collocation of the permanent causes is not reducible to a law, there
being no principle known to us as governing the distribution and
relative proportions of the primaeval natural agents.
Uniformities cannot be proved by the Method of Agreement alone to be
laws of causation; they must be tested by the Method of Difference, or
explained deductively. But laws of causation themselves are either
ultimate or derivative. Signs, previous to actual proof by _resolution_
of them, of their being derivative, are, either that we can _surmise_
the existence of a link between the known antecedent and the consequent,
as e.g. in the laws of chemical action; or, that the antecedent is some
very complex fact, the effects of which are probably (since most complex
cases fall under the Composition of Causes) compounded of the effects of
its different elements. But the laws which, though laws of causation,
are thus presumably derivative laws only, need, equally with the
uniformities which are not known to be laws of causation at all, to be
explained by deduction (which they then in turn verify), and are less
_certain_ than when they have been resolved into the ultimate laws.
Consequently they come under the definition of Empirical Laws, equally
with uniformities not known to be laws of causation. However, the latter
are far more _uncertain_; for as, till they are resolved, we cannot tell
on how many collocations, as well as laws, they may not depend, we must
not rely on them beyond the exact limits in which the observations were
made. Therefore, the name _Empirical Laws_ will generally be confined
here to these.