Fallacious Reasoning.
A fallacy is defined as "an unsound argument or mode of arguing which,
while appearing to be decisive of a question, is in reality not so; or a
fallacious statement or proposition in which the error is not readily
apparent. When a fallacy is used to deceive others, it is called
'sophistry,'" It is important that the student should understand the
nature of the fallacy and understand its most common forms. As Jevons
says: "In learning how to do right it is always desirable to be informed
as to the ways in which we are likely to go wrong. In describing to a
man the road which he should follow, we ought to tell him not only the
turnings which he is to take but also the turnings which he is to avoid.
Similarly, it is a useful part of logic which teaches us the ways and
turnings by which people most commonly go astray in reasoning."
In presenting the following brief statement regarding the more common
forms of fallacy, we omit so far as possible the technical details which
belong to text-books on logic.
FALLACIES.
I. _True Collective but False Particular._--An example of this fallacy
is found in the argument that because the French race, collectively, are
excitable, therefore a particular Frenchman must be excitable. Or that
because the Jewish race, collectively, are good business people,
therefore the particular Jew must be a good business man. This is as
fallacious as arguing that because a man may drown in the ocean he
should avoid the bath, basin, or cup of water. There is a vast
difference between the whole of a thing and its separate parts. Nitric
acid and glycerin, separately, are not explosive, but, combined, they
form nitro-glycerin, a most dangerous and powerful explosive. Reversing
this form of illustration, we remind you of the old saying: "Salt is a
good thing; but one doesn't want to be put in pickle."
II. _Irrelevant Conclusion._--This fallacy consists in introducing in
the conclusion matter not contained in the premises, or in the confusing
of the issue. For instance: (1) All men are sinful; (2) John Smith is a
man; therefore (3) John Smith is a horse thief. This may sound absurd,
but many arguments are as fallacious as this, and for the same reason.
Or another and more subtle form: (1) All thieves are liars; (2) John
Smith is a liar; therefore (3) John Smith is a thief. The first example
arises from the introduction of new matter, and the last from the
confusion of the issue.
III. _False Cause._--This fallacy consists in attributing cause to a
thing which is merely coincident with, or precedent to, the effect. For
instance: (1) The cock crows just before or at the moment of sunrise;
therefore (2) the cock-crowing is the cause of the sunrise. Or, again:
(1) Bad crops followed the election of a Whig president; therefore (2)
the Whig party is the cause of the bad crops. Or, again: (1) Where
civilization is the highest, there we find the greatest number of high
hats; therefore (2) high hats are the cause of civilization.
IV. _Circular Reasoning._--In this form of fallacy the person reasoning
or arguing endeavors to explain or prove a thing by itself or its own
terms. For instance: (1) The Whig party is honest because it advocates
honest principles; (2) the Whig principles are honest because they are
advocated by an honest party. A common form of this fallacy in its phase
of sophistry is the use of synonyms in such a manner that they seem to
express more than the original conception, whereas they are really but
other terms for the same thing. An historic example of circular
reasoning is the following: (1) The Church of England is the true
Church, because it was established by God; (2) it must have been
established by God, because it is the true Church. This form of
sophistry is most effective when employed in long arguments in which it
is difficult to detect it.
V. _Begging the Question._--This fallacy arises from the use of a false
premise, or at least of a premise the truth of which is not admitted by
the opponent. It may be stated, simply, as "_the unwarranted assumption
of a premise, generally the major premise_." Many persons in public life
argue in this way. They boldly assert an unwarranted premise, and then
proceed to argue logically from it. The result is confusing to the
average person, for, the steps of the reasoning being logical, it seems
as if the argument is sound, the fact of the unwarranted premise being
overlooked. The person using this form of sophistry proceeds on Aaron
Burr's theory of truth being "that which is boldly asserted and
plausibly maintained."
Bulwer makes one of his characters mention a particularly atrocious form
of this fallacy (although an amusing one) in the following words:
"Whenever you are about to utter something astonishingly false, always
begin with: 'It is an acknowledged fact,' etc. Sir Robert Filmer was a
master of this manner of writing. Thus with what a solemn face that
great man attempted to cheat. He would say: '_It is a truth undeniable_
that there cannot be any multitude of men whatsoever, either great or
small, etc., but that in the same multitude there is one man among them
_that in nature hath a right to be King of all the rest--as being the
next heir of Adam_!'"
Look carefully for the major premise of propositions advanced in
argument, spoken or written. Be sure that the person making the
proposition is not "begging the question" by _the unwarranted assumption
of the premise_.
GENERAL RULE OF INFERENCE.
Hyslop says concerning valid inferences and fallacious ones: "We cannot
infer _anything_ we please from any premises we please. We must conform
to certain definite rules or principles. Any violation of them will be a
fallacy. There are two simple rules which should not be violated: (1)
_The subject-matter in the conclusion should be of the same general kind
as in the premises_; (2) _the facts constituting the premises must be
accepted and must not be fictitious_." A close observance of these rules
will result in the detection and avoidance of the principal forms of
fallacious reasoning and sophistry.
SOPHISTICAL ARGUMENTS.
There are a number of tricky practices resorted to by persons in
argument, that are fallacious in intent and result, which we do not
consider here in detail as they scarcely belong to the particular
subject of this book. A brief mention, however, may be permitted in the
interest of general information. Here are the principal ones:--
(1) Arguing that a proposition is correct because the opponent cannot
prove the contrary. The fallacy is seen when we realize that the
statement, "The moon is made of green cheese," is not proved because we
cannot prove the contrary. No amount of failure to _disprove_ a
proposition really _proves_ it; and no amount of failure to _prove_ a
proposition really _disproves_ it. As a general rule, the burden of
proof rests upon the person stating the proposition, and his opponent is
not called upon to disprove it or else have it considered proved. The
old cry of "You cannot _prove_ that it is _not_ so" is based upon a
fallacious conception.
(2) Abuse of the opponent, his party, or his cause. This is no real
argument or reasoning. It is akin to proving a point by beating the
opponent over the head.
(3) Arguing that an opponent does not live up to his principles is no
argument against the principles he advocates. A man may advocate the
principle of temperance and yet drink to excess. This simply proves that
he preaches better than he practices; but the truth of the principle of
temperance is not affected in any way thereby. The proof of this is
that he may change his practices; and it cannot be held that the change
of his personal habits improves or changes the nature of the principle.
(4) Argument of authority is not based on logic. Authority is valuable
when really worthy, and merely as corroboration or adding weight; but it
is not logical argument. The _reasons_ of the authority alone constitute
a real argument. The abuse of this form of argument is shown, in the
above reference to "begging the question," in the quotation from Bulwer.
(5) Appeal to prejudice or public opinion is not a valid argument, for
public opinion is frequently wrong and prejudice is often unwarranted.
And, at the best, they "have nothing to do with the case" from the
standpoint of logic. The abuse of testimony and claimed evidence is also
worthy of examination, but we cannot go into the subject here.
FALLACIES OF PREJUDICE.
But perhaps the most dangerous of all fallacies in the search for truth
on the part of the most of us are those which arise from the
following:--
(1) The tendency to reason from what we feel and wish to be true, rather
than from the actual facts of the case, which causes us unconsciously to
assume the mental attitude of "if the facts agree with our likes and
pet theories, all is well; if they do not, so much the worse for the
facts."
(2) The tendency in all of us to perceive only the facts that agree with
our theories and to ignore the others. We find that for which we seek,
and overlook that which does not interest us. Our discoveries follow our
interest, and our interest follows our desires and beliefs.
The intelligent man or woman realizes these tendencies of human nature
and endeavors to avoid them in his or her own reasoning, but is keenly
conscious of them in the arguments and reasoning of others. A failure to
observe and guard one's self against these tendencies results in
bigotry, intolerance, narrowness, and intellectual astigmatism.