n news of war makes the city expect that Consols will fall. These
are examples of the act of inferring, or of inference as a process; and
with inference in this sense Logic has nothing to do; it belongs to
Psychology to explain how it is that our minds pass from one perception
or thought to another thought, and how we come to conjecture, conclude
and believe (_cf._ chap. i. Sec. 6).

In the second sense, 'inference' means not this process of guessing or
opining, but the result of it; the surmise, opinion, or belief when
formed; in a word, the conclusion: and it is in this sense that
Inference is treated of in Logic. The subject-matter of Logic is an
inference, judgment or conclusion concerning facts, embodied in a
proposition, which is to be examined in relation to the evidence that
may be adduced for it, in order to determine whether, or how far, the
evidence amounts to proof. Logic is the science of Reasoning in the
sense in which 'reasoning' means giving reasons, for it shows what sort
of reasons are good. Whilst Psychology explains how the mind goes
forward from data to conclusions, Logic takes a conclusion and goes back
to the data, inquiring whether those data, together with any other
evidence (facts or principles) that can be collected, are of a nature to
warrant the conclusion. If we think that the night will be stormy, that
John Doe is of an amiable disposition, that water expands in freezing,
or that one means to national prosperity is popular education, and wish
to know whether we have evidence sufficient to justify us in holding
these opinions, Logic can tell us what form the evidence should assume
in order to be conclusive. What _form_ the evidence should assume: Logic
cannot tell us what kinds of fact are proper evidence in any of these
cases; that is a question for the man of special experience in life, or
in science, or in business. But whatever facts constitute the evidence,
they must, in order to prove the point, admit of being stated in
conformity with certain principles or conditions; and of these
principles or conditions Logic is the science. It deals, then, not with
the subjective process of inferring, but with the objective grounds that
justify or discredit the inference.

Sec. 2. Inferences, in the Logical sense, are divided into two great
classes, the Immediate and the Mediate, according to the character of
the evidence offered in proof of them. Strictly, to speak of inferences,
in the sense of