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Among the various authorities (upon this question of quantifying the predicate) collected by Sir W. Hamilton in the valuable Appendix to his 'Lectures on Logic,' we find one (p. 311) which takes the same ground of objection as Mr Mill, in these words:—'The cause why the quantitative note is not usually joined with the predicate, is, that there would thus be two quæsita at once; to wit, whether the predicate were affirmed of the subject, and whether it were denied of everything beside. For when we say, all man is all rational, we judge that all man is rational, and judge likewise that rational is denied of everything but man. But these are, in reality, two different quæsita; and therefore it has become usual to state them, not in one, but in two several propositions. And this is self-evident, seeing that a quæsitum, in itself, asks only—Does or does not this inhere in that? and not Does or does not this inhere in that, and at the same time inhere in nothing else?'
The author of this just and sagacious remark—much surpassing what the other writers quoted in the Appendix say—was a Jew who died at Perpignan in or near 1370, named Levi Ben Gerson or Gersonides. An interesting account of this man, eminent as a writer and thinker in his age, will be found in a biography by Dr Joel, published at Breslau in 1862, 'Levi Ben Gerson als Religions—philosoph.' He distinguished himself as a writer on theology, philosophy, and astronomy; he was one of the successors to the free speculative vein of Maimonides, and one of the continuators of the Arabic Aristotelian philosophy. He both commented on and combated the doctrines of Averroes. Dr Joel thinks that he died earlier than 1370.
