ick,
conscious or unconscious, consists in getting assent to a statement
with a qualification and proceeding to argue as if it had been
conceded without qualification, and _vice versa_. For example, it
being admitted that culture is good, a disputant goes on to argue
as if the admission applied to some sort of culture in special,
scientific, aesthetic, philosophical or moral. The fallacy was also
known as _Fallacia Accidentis_. Proving that the Syllogism is useless
for a certain purpose, and then claiming to have proved that it
is useless for any purpose is another example. Getting a limited
admission and then extending it indefinitely is perhaps the more
common of the two forms. It is common enough to deserve a shorter
name.

The _Fallacia Consequentis_, or _Non-Sequitur_, which consists
specially in ignoring the possibility of a plurality of causes, has
already been partly explained in connexion with the Hypothetical
Syllogism, and will be explained further in the Logic of Induction.

_Post hoc ergo proper hoc_ is a purely Inductive Fallacy, and will be
explained in connexion with the Experimental Methods.

There remain the two typical Deductive Fallacies, PETITIO PRINCIPII
(Surreptitious Assumption) and IGNORATIO ELENCHI (Irrelevant Argument)
about which we must speak more at length.

The phrase of which Petitio Principii or Begging the Question is a
translation--[Greek: to en arche aiteisthai]--was applied by Aristotle
to an argumentative trick in debate by Question and Answer. The
trick consisted in taking for granted a proposition necessary to
the refutation without having obtained the admission of it. Another
expression for the same thing--[Greek: to en arche lambanein]--taking
the principle for granted--is more descriptive.

Generally speaking, Aristotle says, Begging the Question consists in
not demonstrating the theorem. It would be in accordance with this
general description to extend the name to all cases of tacitly or
covertly, unwittingly to oneself or to one's opponent, assuming
any premiss necessary to the conclusion. It is the fallacy of
Surreptitious Assumption, and all cases of Enthymematic or Elliptical
argument, where the unexpressed links in the chain of argument are not
fully understood, are examples of it. By contrast, the articulate and
explicit Syllogism is an _Expositio Principii_. The only remedy for
covert assumptions is to force them into the light.[1]

_Ignoratio Elenchi_, ignoring