A System of Logic, Ratiocinative and Inductive (Vol. 1 of 2)
John Stuart Mill · en
The statement, that the uniformity of the course of nature is the ultimate
major premiss in all cases of induction, may be thought to require some
explanation. The immediate major premiss in every inductive argument, it
certainly is not. Of that, Archbishop Whately’s must be held to be the
correct account. The induction, “John, Peter, &c., are mortal, therefore
all mankind are mortal,” may, as he justly says, be thrown into a
syllogism by prefixing as a major premiss (what is at any rate a necessary
condition of the validity of the argument) namely, that what is true of
John, Peter, &c, is true of all mankind. But how come we by this major
premiss? It is not self-evident; nay, in all cases of unwarranted
generalization, it is not true. How, then, is it arrived at? Necessarily
either by induction or ratiocination; and if by induction, the process,
like all other inductive arguments, may be thrown into the form of a
syllogism. This previous syllogism it is, therefore, necessary to
construct. There is, in the long run, only one possible construction. The
real proof that what is true of John, Peter, &c., is true of all mankind,
can only be, that a different supposition would be inconsistent with the
uniformity which we know to exist in the course of nature. Whether there
would be this inconsistency or not, may be a matter of long and delicate
inquiry; but unless there would, we have no sufficient ground for the
major of the inductive syllogism. It hence appears, that if we throw the
whole course of any inductive argument into a series of syllogisms, we
shall arrive by more or fewer steps at an ultimate syllogism, which will
have for its major premiss the principle, or axiom, of the uniformity of
the course of nature.(61)
It was not to be expected that in the case of this axiom, any more than of
other axioms, there should be unanimity among thinkers with respect to the
grounds on which it is to be received as true. I have already stated that
I regard it as itself a generalization from experience. Others hold it to
be a principle which, antecedently to any verification by experience, we
are compelled by the constitution of our thinking faculty to assume as
true. Having so recently, and at so much length, combated a similar
doctrine as applied to the axioms of mathematics, by arguments which are
in a great measure applicable to the present case, I shall defer the more
particular discussion of this controverted point in regard to the
fundamental axiom of induction, until a more advanced period of our
inquiry.(62) At present it is of more importance to understand thoroughly
the import of the axiom itself. For the proposition, that the course of
nature is uniform, possesses rather the brevity suitable to popular, than
the precision requisite in philosophical, language: its terms require to
be explained, and a stricter than their ordinary signification given to
them, before the truth of the assertion can be admitted.