Commentary Aristotle Posterior Analytics
Then, at: thus, when our question (90b26) he clarifies the questions he laid down; and first of all the complex ones.
To understand this it should be noted that science bears only on the true, and the true is not signified except by an enunciation; therefore, only the enunciation can be scientifically knowable and so inquirable. But, as it is stated in On Interpretation II, the enunciation is formed in two ways: in one way from a name and a verb without an appositive, as when it is stated that man is; in another way when some third item is set adjacent, as when it is stated that man is white. Therefore, the questions we form can be reduced either to the first type of enunciation so that we get, as it were, a simple question; or to the second type, and then the question will be, as it were, complex or put in number, because, namely, the question concerns the putting together of two items.
According to this latter type a twofold question can be formed.
One of them is whether this is true which is stated. This question he expounds first, saying that when we ask concerning some thing whether that thing is this or that, so that in effect we are somehow putting it in number, namely, by taking two things one of which is predicate and the other subject, as when we ask if the sun is failing because of an eclipse or not, and is man an animal or not, then we are said to ask 'quia': not in the sense that the word 'quia' functions as a question mark, but because we are asking in order to find out 'quia' [that is, that] it is so. An indication of this is that when we have discovered it through demonstration, we cease our questioning; and if we had known it at the very beginning, we would not have asked whether it is so. But inquiry does not cease until that is obtained which was asked. And so, since the question in which we ask whether this is this ceases once we have certified that it is so, it is clear what a question of this kind asks.
Then he clarifies the next question which also puts in number, by saying that when we know that it is so, we ask propter quid [that is, why] it is so, at: on the other hand, when we know (90b28).
For example, when we know 'that' the sun is failing through an eclipse and that the earth is moved during an earthquake, we ask 'why' the sun is failing or why the earth is being moved. Therefore, we ask it in this way, namely, by putting in number.
Then he clarifies the other two questions which do not put in number but are simple, at: but for some objects (90b32).
And he says that we ask certain things in a manner different from the aforesaid questions, namely, by not putting in number; as when we ask whether or not there be centaurs, for in this case the question we ask concerning the centaur is simply whether it exists and not whether the centaur be this—say white—or not. And just as when we knew that this is this, we then asked why, so once we know of something simply that it is, we ask what it is, for example, "what is God" or "what is man".
These, then, and so many are the things we ask; and when we have found the answer, we are said to know scientifically.
Then, at: now, when we ask (90b38) he shows how the aforesaid questions are related to the middle.
Concerning this he does three things.
First, he states what he intends.
Second, he explains what he had said, at: by distinguishing the fact (91a2; [413]).
Third, he proves his proposition, at: we conclude that in all our inquiries (91a5; [414]).
In regard to the first it should be noted that two of the aforesaid questions put in number and two do not. From the first member of each of these groups, he forms another grouping composed of the question 'that it is' and the question 'if it is'.
And he says that when we ask that this is this, or when we simply ask concerning something, if it is, we are not asking anything else than whether or not a middle is to be found of that which we ask.
This is something not conveyed by the form of the question. For when I ask "whether the sun is eclipsed" or "whether man exists", it is not obvious from the form of the question that I am asking whether there is some middle by which it might be demonstrated that the sun is eclipsed or that man exists; but if the sun is eclipsed or man does exist, the consequence is that some middle can be found to demonstrate the things which are inquired. For no one forms a question concerning immediate things which, although they are true, do not have a middle, since things of this sort, being evident, do not fall under a question. Thus, therefore, one who asks whether this is this or whether this absolutely is, as a consequence is asking whether there is a middle of this sort. For in the question 'if it is' or 'that it is', one is asking whether that which is a middle exists, because that which is the middle is the reason of that concerning which one asks whether this is this or simply whether it is, as will be explained below. Nevertheless the question is not being asked under the aspect of middle.
Now it happens that having found the answer to what is asked by these two questions, one knows either 'that it is' or 'if it is': one of which consists in knowing the existence absolutely; but the other in part, as when we know that man is white, because to be white does not signify the existence of man in his entirety but signifies him to be something. This is why when a man is becoming white, we do not say that he is coming to be absolutely, but in a qualified sense. But when it is asserted that "man is", his existence is signified absolutely, so that when a man comes to be, he is said to become absolutely. Therefore, when we know 'that it is' and ask 'why it is', or when we know 'if it is' and ask 'what it is', we are asking what is the middle.
And as in the other cases, so here, this is gathered not from the form of the question but by way of concomitance. For one who seeks the cause why the sun is eclipsed is not seeking it as a middle which demonstrates, but he is seeking that which is a middle, because it is by way of consequence that once he has it, he can demonstrate. And the same applies to the question 'what is it'.
Then, at: by distinguishing the fact (91a2) he manifests what he had said, namely, that 'that it is' and 'if it is' differ as in part and absolutely differ. For when we inquire whether the moon is waning or waxing, it is a question in part, since in a question of this type we are asking if the moon is something, namely, is it waning or has it waxed or not. But when we ask whether the moon exists or whether it is night, the question bears on existence absolutely.
Then he proves his point, namely, that the aforesaid questions pertain to the middle, at: we conclude that in all (91a5).
First, he proves it with a reason.
Second, with a sign, at: cases in which the ‘middle’ (91a5; [416]).