SOPHISM, in Logic, a specious argument having
the appearance of truth, but leading to falsehood. Sop-
hisms are reduced by Aristotle into eight classes, an ar-
rangement so just and comprehensive, that it is equally
proper in present as in former times. 1. Ignoratio elenchi,
in which the sophist seems to determine the question,
while he does it only in appearance. Thus the question,
"Whether the excess of wine be hurtful?" seems to be
determined by proving, that wine revives the spirits and
gives a man courage: but the principal point is here kept
out of sight; for still it may be hurtful to health, to for-
tune, and reputation. 2. Petito principii, a begging of
the question, or taking for granted that which remains
to be proved, as if any one should undertake to prove
that the soul is extended through all the parts of the
body, because it resides in every member. This is af-
firming the same thing in different words. 3. Reasoning
in a circle; as when the Roman Catholics prove the
Scriptures to be the word of God by the authority of
the church, and the authority of the church from the
Scriptures. 4. Non causa pro causa, or the assigning of
a false cause to any effect. Thus the supposed prin-
ciple, that nature abhors a vacuum, was applied to ex-
plain the rising of water in a pump before Galileo
discovered that it was owing to the pressure of the
atmosphere. In this way the vulgar ascribe accidents
to divine vengeance, and the heresies and infidelity
of modern times are said to be owing to learning. 5. Fallacia accidentis, in which the sophist represents
what is merely accidental as essential to the nature of
the subject. This is nearly allied to the former, and is
committed by the Mahometans and Roman Catholics.
The Mahometans forbid wine, because it is sometimes
the occasion of drunkenness and quarrels; and the Ro-
man Catholics prohibit the reading of the Bible, be-
cause it has sometimes promoted heresies. 6. By deduc-
ing an universal assertion from what is true only in par-
ticular circumstances, and the reverse: thus some men
argue, "transcribers have committed many errors in
copying the Scriptures, therefore they are not to be de-
pended on." 7. By asserting any thing in a compound
sense which is only true in a divided sense; so when the
Scriptures assure us, that the worst of sinners may be
saved, it does not mean that they shall be saved while
they remain sinners, but that if they repent they may be
saved. 8. By an abuse of the ambiguity of words.
Thus Mr Hume reasons in his Essay on Miracles:
"Experience is our only guide in reasoning concerning
matters of fact; now we know from experience, that
the laws of nature are fixed and invariable. On the
other hand, testimony is variable and often false; there-
fore since our evidence for the reality of miracles rests
solely on testimony which is variable, and our evidence
for the uniformity of the laws of nature is invariable,
miracles are not to be believed." The sophistry of this
reasoning depends on the ambiguity of the word expe-
rience, which in the first proposition signifies the max-
ims which we form from our own observation and re-
flection; in the second it is confounded with testimo-
ny; for it is by the testimony of others, as well as our
own observation, that we learn whether the laws of na-
ture are variable or invariable. The Essay on Miracles
may be recommended to those who wish to see more ex-
amples of sophistry; as we believe most of the eight
species of sophisms which we have mentioned are well
illustrated by examples in that essay.