An outline of the necessary laws of thought; a treatise on pure and applied logic . another is ufed as a diftin£tivemark of that part which it overlaps. If (for an eafyexample) in analyfing our notion of the red-flower-ing currant {Ribes fanguineum) we regard currantas the genus and u red-flowering as the difference,we may alfo regard red-flowering as a wide genus,wider in fa£t than currant, and therefore we mayfay that our notion of the plant is formed from theconcurrence of two genera.* This we fuppofe to be Ariftotles meaning in con-sidering difference as having the nature of we a
An outline of the necessary laws of thought; a treatise on pure and applied logic . another is ufed as a diftin£tivemark of that part which it overlaps. If (for an eafyexample) in analyfing our notion of the red-flower-ing currant {Ribes fanguineum) we regard currantas the genus and u red-flowering as the difference,we may alfo regard red-flowering as a wide genus,wider in fa£t than currant, and therefore we mayfay that our notion of the plant is formed from theconcurrence of two genera.* This we fuppofe to be Ariftotles meaning in con-sidering difference as having the nature of we are now to notice that he examines and ar-ranges his four Predicable claffes according to thisteft—Can each of them, without logical fault, changeplaces with its fubjeft. In other words, is each ofthem co-extenfive with its fubjeft or not ? The re-fults of the teft will be apparent from an account ofeach of the claffes. * Let A be the clafs of red-flowering things, B the clafscurrant ; then x, the part of each which is in the other, willbe our notion of red-flowering LAWS OF THOUGHT. 149 Definition # is a defcription which manifefts com-pletely the nature of the thing defined. Such a de-fcription would of courfe enable us to identify thefubje£t, and to diftinguifh it from all other therefore it muft be applicable only to the fub-je£t, otherwife it manifefts, not the peculiar natureof the thing defined, but its common nature, the quali-ties which it fhares with other things. As beingapplicable to the fubjeft and to no other notion, it isco-extenfive with it, and therefore may change placeswith it in the judgment. It is juft as true to fay thatu every rational animal is man as that every manis a rational animal. But if we faid that man isa warm-blooded animal, or that man is a civilizedanimal, neither of them would be a definition, norcould the predicate in either become the fubjeft,without fome limitation. The former is a defcrip-tion that applies to m
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Keywords: ., bookcentury1800, bookdecade1850, bookpublishere, booksubjectlogic
