Book II of the Posterior Analytics. Treatise I. Chapter I.

BOOK II OF THE POSTERIOR ANALYTICS. TREATISE I. On the number of demonstrable knowable things in demonstrative science. CHAPTER I. That the number of things truly knowable is taken from the number of questions, and how many and what the questions are. Now that those things have been had which pertain to the principles of demonstration, from which and of what kind demonstration is made, one must hand down the faculty of demonstrating in any demonstrable thing, which art, I say, consists in the discovery of the demonstrative middle. For we kept this mode in the prior resolutory or analytic books, first showing from what things and of what sort the syllogism is, and afterward handing down the art of syllogizing through discoveries of the syllogistic middle, and the faculty and power of syllogizing. But before we teach the discovery of the demonstrative middle, because every middle consists in this, that through it one may come by demonstration to knowledge of a knowable complex thing, therefore one must first teach what the truly knowable is, and how many knowable things there are in genus which can be known through demonstration. For this science is the end of the inquiry of the demonstrative middle, and, as Aristotle says, one must set the end beforehand, so that we may know that every following treatise is directed to it, just as an archer sets beforehand the target to which he directs the arrow; and this is Avicenna's example in this place. Moreover, because the question, in receiving science, precedes the thing known, since a question arises from wonder and therefore stirs one to inquire into the cause in that which is demonstrable, it is therefore fitting to begin from the question from which everyone who rightly inquires through philosophy begins to philosophize. Moreover, because the question and the thing known are the same in subject, but according to account the question is preliminary to the thing known according to the act in which the one who truly receives science of admirable things first wonders, therefore Aristotle says in the first book of First Philosophy that from wondering, both then and now, philosophizing was begun. Beginning from the question, we say that questions, which, as Alfarabi says, are about demonstrable things and not other things, are equal in number to all those things which are truly known and known through demonstration. And if they are truly known, or comprehended by a better habit than science, and are not demonstrable, as principles and things of this kind are, there will not be questions about these which are left concerning them, because all such things are as was determined in what has been had before. <marginal-label>The faculty of demonstrating consists in the discovery of the demonstrative middle.</marginal-label> <marginal-label>Why he begins from the question.</marginal-label> <marginal-label>The question is preliminary to the thing known.</marginal-label> <marginal-label>He removes a doubt.</marginal-label> <marginal-label>Questions are multiplied according to the form of things known.</marginal-label> Moreover, it must be noted that questions are not multiplied according to things truly known according to the matter of knowable things; for in this way questions are fewer than things truly known, but questions are multiplied according to the form of things known. For whatever things we truly know are not sophistical things, or from those things that are known per accidens, or even known opinably, as topical things are; but they are, as Averroes says, known either through demonstration, as complex things, or through the things that are in demonstration, as through the middle which is definition. Thus the that is known from the conclusion of demonstration; but science on-account-of-what is known through the middle of the most powerful demonstration according as it actually mediates between the extremes; but science what is had through definition not insofar as it mediates, but insofar as it is definition; and science whether it is is left from it. Therefore because, as Alfarabi says, the question whether it is, or if it is, cannot be terminated by a categorical proposition, because the subject of the question is not supposed or known, to which the predicate may be referred by a categorical proposition; and therefore the question whether it is is terminated by a conditional, just as the known thing is left to be, when what it is is now known ¹. This is Alfarabi's opinion. Therefore in this way the questions of those things that are demonstrated, that is, that are received through demonstration and through the principles of demonstrations, are equal in number, species, and form to those things which we truly know, that is, receive through demonstration, or to those things which are in demonstration. Nevertheless there are many other questions according to number which incomparably exceed the number of things truly known. But concerning demonstratively knowable things we ask four things, namely that it is, and on account of what it is, and whether it is, and what it is. And when that it is is said, it is understood of a true complex. Hence another translation has, in place of that it is this, whether it belongs to this. For the question that it is this supposes a complex; and therefore if we ask that it is, with this we ask concerning that of which it is. But that it is this is this being this, because otherwise it would not be said that it itself is. Hence the question that it is is the question whether this is this, or whether this predicate which is stated belongs to this. Therefore this is the first question about a complex, in which this is enunciated of this; and this is concluded in demonstration that. For that demonstration simply concludes this of this. <marginal-label>The question that it is is concluded through demonstration that it is.</marginal-label> But one knowing this, that it belongs to this, does not rest from asking; indeed, we still ask concerning the complex on account of what it belongs, wishing to know the cause of the inherence of that which belongs; and this is concluded in demonstration on-account-of-what. And those two questions are about the complex and about subject and predicate, and are terminable through demonstration either that or on-account-of-what. But concerning the simple or incomplex, whether concerning the subject or concerning the predicate which is a property, we ask whether it is, that is, whether it exists, and what it is. Hence another translation has whether it is and what it is; and what is said, if it is or whether it is, asks the being of that which is. On account of this Avicenna says that since being simply, and not being this or that, is first being, which supposes nothing,

before itself, this question is not terminable except through the first cause, which causes in such a way because it supposes nothing causing before itself; for to be a cause is the effect of the first being which is the first cause. And because it is unknown according to being of this kind, therefore it is not determinable except through a conditional proposition and not through a categorical proposition, as was said in the things previously had. <marginal-label>The cause simply first does not fall in demonstration.</marginal-label> But the first cause which is simply first does not fall in demonstration, because it is proportional to nothing. But knowing the being of what is, we ask what it is, that is, its quiddity through definition. For the being that we ask about is either a composite terminable through demonstration, through which one arrives at knowledge of a complex, or it is a complex, or it is simple and incomplex. If indeed it is a complex, it is terminated either by demonstration that, or by demonstration on account of what, as has been said. But if it is a question of an incomplex thing, either inquiry is made about simple being or about quiddity. And about being inquiry is made through the question in which this verb is, taken simply, is one of the extremes and not the third adjacent, as concerning a human being we ask whether he exists or not. For then we ask simply whether a human being has being simply, according as simple being is the concept which is received through this, and a concept undetermined to this or that. But by asking what it is, we ask about the quiddity of that which is; and that question supposes the being which is the subject of that quiddity. And therefore the question if it is is terminated through a conditional by the determination of the question that asks what it is. Therefore these are the questions about the simple and the composite which can be asked in demonstrative matters. And in expounding these we add that when we ask about something through the question that it is, whether this or this is, that is, whether this predicate belongs to that or not, we ask while placing in number. But certain Commentators say that being does not place in number where inquiry is made simply about being through the question if it is or whether it is; rather, inquiry is made simply about undetermined being. But it is placed in number and contracted so that it may be numbered with another, when it is asked whether it is this or that being, not received in common and according as it is signified in this verb is, but another adjacent in it made numerable through something added, because by a substantial or accidental difference it is divided so that it can fall into number. For difference is always the cause of number. Therefore the question if it is, or whether it is, does not place in number. <marginal-label>How the question if it is does not place in number according to Avicenna and Alfarabi.</marginal-label> <marginal-label>Difference is always the cause of number.</marginal-label> But when that it is is asked, that is, whether it is this or that, in the question it supposes the subject that is imported through what is said, if this is this or that, and inquiry is made about the inherence of the predicate in the subject. But the predicate is a substantial or accidental difference, through which the being of the subject is placed in number. This is the true exposition, and it belongs to Avicenna and Alfarabi. <marginal-label>Another exposition, how the question that it is places in number, but not the question if it is.</marginal-label> Yet certain people say that the question that, or whether it is this or that, places in number for this reason, because it asks about the inherence of the predicate in the subject; and thus it places in number, because the predicate and the subject are two. But the question if it is, or whether it is, asks only about one thing, that is, about being, not supposing a subject. But the first exposition is better, because even being is referred to that which is as to a subject; but this is true, that the subject's being is not determined. But the example of the question that it is, which places in number, is when we ask, as whether the sun is eclipsed or not. For then we ask whether such a predicate belongs to such a subject, since the predicate and the subject are diverse numbered natures, through the other of which, that is, the predicate, the being of the subject is determined and distinguished and numbered; and then we ask the very that, whether it belongs to that to which it is said to belong, which is concluded through a demonstration or syllogism simply inferring that. But the sign of this, namely that we ask nothing else, is that through the demonstration of the question that the sun is eclipsed, we pause, not inquiring further about this that; and if at the beginning before the question we knew that the sun is eclipsed, we would not ask whether it was eclipsed or not. But inquiry is made about that which, when it is had and known, there is a pause in the question. Therefore this is the question that. But when we know the very that, then at once, as Avicenna says, we are in anxiety and wonder what the cause is, that such a predicate belongs to such a subject; and from that wonder, anxiety, or suspension toward the cause, we ask on account of what it is, that is, on account of what cause such a predicate belongs to the subject, as, knowing that the sun is eclipsed, or that the earth is moved and trembles, we ask on account of what the sun is eclipsed, and on account of what the earth trembles or is moved. And from this, as Averroes says, a human being begins to philosophize; for first the that fails from sensible and common cognition; but to be suspended and to wonder makes one seek the cause; and this is to philosophize. Therefore we ask these two things in this way about a complex which is concluded through demonstration. And we set forth these two questions first, because they are terminable through demonstration, about which we intend here, and are more joined to demonstration, although the other two are prior according to the way of nature. <marginal-label>Why he set forth the composite questions.</marginal-label> Certain incomplex things, which are terminable through those things that are in demonstration and not properly through the conclusion of demonstration, we ask by another mode of question, or through other questions. For we ask about the subject considered in itself, and thus we ask if it is or not, or whether it is, whether the centaur is or is not, or if God is or is not. But I speak of this if it is or is not simply; for such a question asks simply about undetermined being, or being taken without determination, according as it is signified through this verb is, insofar as it is one adjacent. But then we do not ask about being through some difference determining the subject, as whether it is white or is not white, or whether this is a human being or is not a human being; and therefore this question does not place in number, because it does not distinguish and divide. But the cause of every number is distinction and division. Nevertheless this question is not determined by demonstration, but is determined consequently and through a condition by the consequent question. But knowing that it is, that is, if it is, to which the answer is that it is, that is, that it is absolutely and confusedly, then, because the intellect does not rest in confusion, we are suspended by wonder and ask what it is, as, therefore, what is God, and what is a human being? Hence the question if it is is related to the question what it is in the simple as the question that is related to the question on account of what it is in the complex; and this is because, knowing the prior one, we are suspended by wonder toward the second. And just as in the question on account of what the science of the question that is perfected, so in the science of the question what it is the science of the question if it is, or whether it is, is perfected. And just as sense is the way to cognition for that, but in the science on account of what demonstration is the way to knowing, so sense is the way for knowing if it is, and definition, which is placed in demonstration, is the way for knowing what it is. Therefore the things that indeed we first ask in the desire of knowing, and the things that, finding them as truly known, we know through the determination of questions, are these things which have been said and as many as have been said. For thus the number also of things truly known is concluded in the number of questions, and thus questions are equal in number to those things which we truly know; and we ask four things; therefore things truly known are four. And conversely the number of questions is syllogized from the number of things truly known. Thus questions are equal in number to those things which we truly know; but we truly know four things; therefore we ask four things. Thus, therefore, the understanding of the first proposition is clear concerning questions and things known, and their equality according to number.