A hot skin, quick pulse, intense thirst have invariably in my
experience coexisted with fever; the person now examined exhibits
these symptoms, so I infer that he has a fever.
Great width of skull between the ears is invariably found united with
a destructive temperament; this animal's skull is very wide between
the ears; hence it may be concluded that he has a destructive
temperament.
Cloven feet belong universally--_i.e._ as far as our experience
goes--to horned animals; we may conclude that this fossil animal,
since it appears to have had cloven feet, was horned.
I.
Cloven feet | inhere with horns
-------------------------+-------------------
Fossil animal appears to | _it is probable he
have had cloven feet | had horns_
When an architect, contemplating the fragments of a building, restores
it in imagination after the analogy of similar buildings, we have an
argument in inherence. Such speculations are generally too long and
complex for analysis, but an instructive example occurs in Canon
Rawlinson's _Seventh Oriental Monarchy_, which I will venture to
quote, marking the phrases that introduce or express the rational
idea. Observe the difference of style between this, which is real
practical reasoning, and the trivial certainties of Syllogistic.
'What remains of this massive erection [the Takht-i-Khosru,
or palace of Chosroës Anushirwan, at Ctesiphon] is a mere
fragment, which, _to judge from the other extant Sassanian
ruins_, cannot have formed so much as one fourth part of
the original edifice. Nothing has come down to our day but a
single vaulted hall on the grandest scale, together with the
mere outer wall of what no doubt constituted the main facade
of the building. The apartments, which, _according to all
analogy_, must have existed at the two sides, and in the rear,
of the great hall, some of which _should_ have been vaulted,
have wholly perished. _Imagination may supply_ them from the
Firuzabad, or the Mashita palace; but not a trace, even of
their foundations, is extant; and the details consequently are
uncertain, though the general plan can scarcely be doubted. At
each side of the great hall _were probably_ two lateral ones,
communicating with each other, and capable of being entered
either from the hall or from the outer air. Beyond the great
hall _was probably_ a domed chamber equalling it in width,
and opening upon a court, round which were a number of
moderate-sized apartments. The entire building _was no doubt_
an oblong square, of which the shorter sides seem to have
measured 370 feet. It had at least three, and _may not
improbably have had_ a larger number of entrances, since it
belongs to tranquil times and a secure locality.'
***
The most notable argument in the category of concretion is undoubtedly
the inference as to the sphericity of the earth. Next is the
sub-inference by Columbus that China could be reached by sailing
westward from Portugal. If the syllogistic opinion were valid--that a
conclusion must be absolutely true or absolutely false--the expedition
of Columbus was based on a fallacy. Most people think it was eminently
rational.
No one has seen the north or the south poles, and the conviction that
they could be realised, if certain difficulties of transport were
overcome, is a sub-inference of the same character.