institutions. For
we have no record of such an event: and if the institutions of one State
(say the British) include ceremonies, such as the coronation oath and
oath of allegiance, which may be remnants of an original contract, they
may nevertheless be of comparatively recent origin; whereas if the
institutions of another State (say the Russian) contain nothing that
admits of similar interpretation, yet traces of the contract once
existing may long since have been obliterated. Moreover, the actual
contents of the contract not having been preserved, every adherent of
this hypothesis supplies them at his own discretion, 'according to the
dictates of Reason'; and so one derives from it the duty of passive
obedience, and another with equal cogency establishes the right of
rebellion.

To be verifiable, then, an hypothesis must be definite; if somewhat
vague in its first conception (which is reasonably to be expected), it
must be made definite in order to be put to the proof. But, except this
condition of verifiability, and definiteness for the sake of
verifiability, without which a proposition does not deserve the name of
an hypothesis, it seems inadvisable to lay down rules for a 'legitimate'
hypothesis. The epithet is misleading. It suggests that the Logician
makes rules for scientific inquirers; whereas his business is to
discover the principles which they, in fact, employ in what are
acknowledged to be their most successful investigations. If he did make
rules for them, and they treated him seriously, they might be
discouraged in the exercise of that liberty of hypothesising which is
the condition of all originality; whilst if they paid no attention to
him, he must suffer some loss of dignity. Again, to say that a
'legitimate hypothesis' must explain all the facts, at least in the
department for which it is invented, is decidedly discouraging. No doubt
it may be expected to do this in the long run when (if ever) it is
completely established; but this may take a long time: is it meanwhile
illegitimate? Or can this adjective be applied to Newton's corpuscular
theory of light, even though it has failed to explain all the facts?

Sec. 3. Given a verifiable hypothesis, however, what constitutes proof or
disproof?

(1) _If a new agent be proposed, it is desirable that we should be able
directly to observe it, or at least to obtain some evidence of its
existence of a different kind from the very facts which it has been
inv