SOPHISM, in Logic, a specious argument, having the appearance of truth, but leading to falsehood. Sophisms are reduced by Aristotle into eight classes, an arrangement 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 prov ing, that wine revives the spirits and gives a man courage; but the principal point is here kept out of eight, for still it may be hurtful to health, to fortune, and reputation. 2. Petitio 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 affirming the same thing in different words.

3. Reasoning in a circle; as when the Romanists prove the Scriptures to be the word of God by the authority of the church, and the authority of the church from the Scrip tures. 4. Non causa pro causa, or the assigning of a false cause to any effect. Thus the supposed principle, that nature abhors a vacuum, was applied to explain 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 l>e owing to learning. 5. Fallacia accidentis, in which the sophist represents what is merely accidental as essential to the nature of the sub ject. 6. By deducing a universal assertion from what is true only in particular 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. Hume reasons thus, 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; therefore, 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 experience, which in the first proposition signifies the maxims which we form from our own observation and reflection; in the second it is confounded with testimony; for it is by the testimony of others, as well as our own observation, that we learn whether the laws of nature are variable or invariable. The Essay on Miracles may be recommended to those who wish to see more examples of sophistry; as we believe most of the eight species of sophisms which we have mentioned are well illustrated by examples in that essay.