questions. 345

Uncertainty of it. — This kind of reasoning is more
uncertain than inductive reasoning. Jevons speaks of the
similarity between so many circumstances in the case of
Mars and the earth as increasing the probability that the
former is inhabited because the latter is, and at the same
time says that " all we can certainly say is, that if the cir-
cumstances be really similar, and similar germs of life
have been created there as here, there must be inhab-
itants." Need I say that in the very nature of the case
we neither know nor can know anything about whether
" similar germs of life have been created there as here,"
and that our knowledge of the extent to which circum-
stances are similar is so limited that any talk of probability
is absolutely without foundation ? All that the facts war-
rant us in saying is, that for aught we know Mars may be
inhabited, but he who claims to be able to say that it
probably is, lays claim to a larger amount of knowledge
than falls to the lot of mortals.
QUESTIONS ON THE TEXT.
i. What is the difference between induction and generalization?

2. Show that induction presupposes generalization.
3. State and illustrate the two assumptions that underlie nearly
all our inductions.
4. What is the law of Parsimony ?

5. Define and illustrate argument from analogy.
6. What seems to you its logical value?

SUGGESTIVE QUESTION.
Give illustrations from your own experience of over-hasty induc-
tions.
LESSON XXXVIII.
APPERCEPTION.
We have studied sensation, perception, memory, imagi.
