The inquiry, then, whether the property has been correctly rendered or no, should be made by these means. The question, on the other hand, whether what is stated is or is not a property at all, you should examine from the following points of view. For the commonplace arguments which establish absolutely that the property is accurately stated will be the same as those that constitute it a property at all: accordingly they will be described in the course of them.
Firstly, then, for destructive purposes, take a look at each subject of which he has rendered the property, and see (e.g.) if it fails to belong to any of them at all, or to be true of them in that particular respect, or to be a property of each of them in respect of that character of which he has rendered the property: for then what is stated to be a property will not be a property. Thus, for example, inasmuch as it is not true of the geometrician that he 'cannot be deceived by an argument' (for a geometrician is deceived when his figure is misdrawn), it could not be a property of the man of science that he is not deceived by an argument. For constructive purposes, on the other hand, see whether the property rendered be true of every instance, and true in that particular respect: for then what is stated not to be a property will be a property. Thus, for example, in as much as the deion 'an animal capable of receiving knowledge' is true of every man, and true of him qua man, it would be a property of man to be 'an animal capable of receiving knowledge'. commonplace rule means-for destructive purposes, see if the deion fails to be true of that of which the name is true; and if the name fails to be true of that of which the deion is true: for constructive purposes, on the other hand, see if the deion too is predicated of that of which the name is predicated, and if the name too is predicated of that of which the deion is predicated.]
Next, for destructive purposes, see if the deion fails to apply to that to which the name applies, and if the name fails to apply to that to which the deion applies: for then what is stated to be a property will not be a property. Thus (e.g.) inasmuch as the deion 'a living being that partakes of knowledge' is true of God, while 'man' is not predicated of God, to be a living being that partakes of knowledge' could not be a property of man. For constructive purposes, on the other hand, see if the name as well be predicated of that of which the deion is predicated, and if the deion as well be predicated of that of which the name is predicated. For then what is stated not to be a property will be a property. Thus (e.g.) the predicate 'living creature' is true of that of which 'having a soul' is true, and 'having a soul' is true of that of which the predicate 'living creature' is true; and so 'having a soul would be a property of 'living creature'.
Next, for destructive purposes, see if he has rendered a subject as a property of that which is described as 'in the subject': for then what has been stated to be a property will not be a property. Thus (e.g.) inasmuch as he who has rendered 'fire' as the property of 'the body with the most rarefied particles', has rendered the subject as the property of its predicate, 'fire' could not be a property of 'the body with the most rarefied particles'. The reason why the subject will not be a property of that which is found in the subject is this, that then the same thing will be the property of a number of things that are specifically different. For the same thing has quite a number of specifically different predicates that belong to it alone, and the subject will be a property of all of these, if any one states the property in this way. For constructive purposes, on the other hand, see if he has rendered what is found in the subject as a property of the subject: for then what has been stated not to be a property will be a property, if it be predicated only of the things of which it has been stated to be the property. Thus (e.g.) he who has said that it is a property of 'earth' to be 'specifically the heaviest body' has rendered of the subject as its property something that is said of the thing in question alone, and is said of it in the manner in which a property is predicated, and so the property of earth would have been rightly stated.
Next, for destructive purposes, see if he has rendered the property as partaken of: for then what is stated to be a property will not be a property. For an attribute of which the subject partakes is a constituent part of its essence: and an attribute of that kind would be a differentia applying to some one species. E.g. inasmuch as he who has said that 'walking on two feet' is property of man has rendered the property as partaken of, 'walking on two feet' could not be a property of 'man'. For constructive purposes, on the other hand, see if he has avoided rendering the property as partaken of, or as showing the essence, though the subject is predicated convertibly with it: for then what is stated not to be a property will be a property. Thus (e.g.) he who has stated that to be 'naturally sentient' is a property of 'animal' has rendered the property neither as partaken of nor as showing the essence, though the subject is predicated convertibly with it; and so to be 'naturally sentient' would be a property of 'animal'.
