1. Cicero, Academ. ii. pp. 30-96. “Si dicis te mentiri verumque dicis, mentiris. Dicis autem te mentiri, verumque dicis: mentiris igitur.” 2, 3. Ὁ ἐγκεκαλυμμένος. You know your father: you are placed before a person covered and concealed by a thick veil: you do not know him. But this person is your father. Therefore you both know your father and do not know him. 5. Κερατίνης. That which you have not lost, you have: but you have not lost horns; therefore you have horns. 4, 6. Σωρείτης — Φάλακρος. What number of grains make a heap — or are many? what number are few? Are three grains few, and four many? — or, where will you draw the line between Few and Many? The like question about the hairs on a man’s head — How many must he lose before he can be said to have only a few, or to be bald?
These sophisms are ascribed to Eubulides, and belonged probably to the Megaric school both before and after him. But it is plain both from the Euthydêmus of Plato, and from the Topica of Aristotle, that there were many others of similar character; frequently employed in the abundant dialectic colloquies which prevailed at Athens during the fourth and third centuries B.C. Plato and Aristotle handle such questions and their authors contemptuously, under the name of Eristic: but it was more easy to put a bad name upon them, as well as upon the Eleate Zeno, than to elucidate the logical difficulties which they brought to view. Neither Aristotle nor Plato provided a sufficient answer to them: as is proved by the fact, that several subsequent philosophers wrote treatises expressly in reference to them — even philosophers of reputation, like Theophrastus and Chrysippus.[38] How these two latter philosophers performed their task, we cannot say. But the fact that they attempted the task, exhibits a commendable anxiety to make their logical theory complete, and to fortify it against objections.
[38] Diog. L. v. p. 49; vii. pp. 192-198. Seneca, Epistol. p. 45. Plutarch (De Stoicor. Repugnantiis, p. 1087) has some curious extracts and remarks from Chrysippus; who (he says) spoke in the harshest terms against the Μεγαρικὰ ἐρωτήματα, as having puzzled and unsettled men’s convictions without ground — while he (Chrysippus) had himself proposed puzzles and difficulties still more formidable, in his treatise κατὰ Συνηθείας.
Real character of the Megaric sophisms, not calculated to deceive but to guard against deception.
It is in this point of view — in reference to logical theory — that the Megaric philosophers have not been fairly appreciated. They, or persons reasoning in their manner, formed one essential encouragement and condition to the formation of any tolerable logical theory. They administered, to minds capable and constructive, that painful sense of contradiction, and shock of perplexity, which Sokrates relied upon as the stimulus to mental parturition — and which Plato extols as a lever for raising the student to general conceptions.[39] Their sophisms were not intended to impose upon any one, but on the contrary, to guard against imposition.[40] Whoever states a fallacy clearly and nakedly, applying it to a particular case in which it conducts to a conclusion known upon other evidence not to be true — contributes to divest it of its misleading effect. The persons most liable to be deceived by the fallacy are those who are not forewarned:—in cases where the premisses are stated not nakedly, but in an artful form of words — and where the conclusion, though false, is not known beforehand to be false by the hearer. To use Mr. John Stuart Mill’s phrase,[41] the fallacy is a case of apparent evidence mistaken for real evidence: you expose it to be evidence only apparent and not real, by giving a type of the fallacy, in which the conclusion obtained is obviously false: and the more obviously false it is, the better suited for its tutelary purpose. Aristotle recognises, as indispensable in philosophical enquiry, the preliminary wrestling into which he conducts his reader, by means of a long string of unsolved difficulties or puzzles — (ἀπόριαι). He declares distinctly and forcibly, that whoever attempts to lay out a positive theory, without having before his mind a full list of the difficulties with which he is to grapple, is like one who searches without knowing what he is looking for; without being competent to decide whether what he hits upon as a solution be really a solution or not.[42] Now that enumeration of puzzles which Aristotle here postulates (and in part undertakes, in reference to Philosophia Prima) is exactly what the Megarics, and various other dialecticians (called by Plato and Aristotle Sophists) contributed to furnish for the use of those who theorised on Logic.
[39] Plato, Republic, vii. pp. 523 A, 524. τὰ μὲν ἐν ταῖς αἰσθήσεσιν οὐ παρακαλοῦντα τὴν νόησιν εἰς ἐπίσκεψιν, ὡς ἱκανῶς ὑπὸ τῆς αἰσθήσεως κρινόμενα — τὰ δὲ παντάπασι διακελευόμενα ἐκείνην ἐπισκέψασθαι, ὡς τῆς αἰσθήσεως οὐδὲν ὑγιὲς ποιούσης … Τὰ μὲν οὐ παρακαλοῦντα, ὅσα μὴ ἐκβαίνει εἰς ἐναντίαν αἴσθησιν ἅμα· τὰ δ’ ἐκβαίνοντα, ὡς παρακαλοῦντα τίθημι, ἐπειδὰν ἡ αἴσθησις μηδὲν μᾶλλον τοῦτο ἢ τὸ ἐναντίον δηλοῖ. Compare p. 524 E: the whole passage is very interesting.
[40] The remarks of Ritter (Gesch. der Philos. ii. p. 189. 2nd ed.) upon these Megaric philosophers are more just and discerning than those made by most of the historians of philosophy “Doch darf man wohl annehmen, dass sie solche Trugschlüsse nicht zur Täuschung, sondern zur Belehrung für unvorsichtige, oder zur Warnung vor der Seichtigkeit gewöhnlicher Vorstellungsweisen, gebrauchen wollten. So viel ist gewiss, dass die Megariker sich viel mit den Formen des Denken beschäftigten, vielleicht mehr zu Aufsuchung einzelner Regeln, als zur Begründung eines wissenschaftlichen Zusammenhangs unter ihnen; obwohl auch besondere Theile der Logik unter ihren Schriften erwähnt werden.”
This is much more reasonable than the language of Prantl, who denounces “the shamelessness of doctrinarism” (die Unverschämtheit des Doctrinarismus) belonging to these Megarici “the petulance and vanity which prompted them to seek celebrity by intentional offences against sound common sense,” &c. (Gesch. der Logik, pp. 39-40. — Sir Wm. Hamilton has some good remarks on these sophisms, in his Lectures on Logic, Lect. xxiii. p. 452 seq.)
[41] See the first chapter of his book v. on Fallacies, System of Logic, vol. ii.