LECTURE 5 (194 b 16-195 a 27)

PHYSICS DETERMINES WHAT THE CAUSES ARE AND HOW MANY SPECIES OF CAUSES THERE ARE

             176. Having shown what natural science considers, the Philosopher here begins to designate the causes from which it should demonstrate.

             This section is divided into two parts. First he treats the causes. Secondly, where he says, 'Now the causes . . .' (198 a 23), he points out the causes from which natural science should demonstrate.

             Concerning the first part he makes two points. First he shows the need for treating the causes. Secondly, where he says, 'In one sense . . .' (194 b 23), he begins to treat the causes.

             He says, therefore, first that after it has been determined what falls under the consideration of natural science, there remains to be considered the causes--what they are and how many there are.

             This is so because the business of studying nature is not ordered to operation, but to science. For we are not able to make natural things, but only to have science of them.

             Now we do not think that we know anything unless we grasp the 'why', which is to grasp the cause. Hence it is clear that we must observe generation and corruption and every natural change in such a way that we know the causes and that we reduce to its proximate cause each thing concerning which we seek the 'why'.

             He says this because the consideration of causes insofar as they are causes is proper to first philosophy. For a cause insofar as it is a cause does not depend upon matter for its existence, because the nature [ratio] of cause is found also in those things which are separated from matter. But the consideration of causes because of a certain necessity is taken up by the natural philosopher. However he considers causes only insofar as they are the causes of natural mutations.

             177. Next where he says, 'In one sense . . .' (194 b 23), he treats the causes.

             Concerning this he makes three points. First he names the clearly diverse species of causes. Secondly, where he says, 'But chance also . . .' (195 b 31), he treats certain less obvious causes. Thirdly, where he says, 'They differ . . .' (197 a 36), he shows that the causes are neither more nor less.

             The first part is divided into two parts. First he treats the species of causes. Secondly, where he says, 'Now the modes . . .' (195 a 27), he treats the modes of diverse causes in each species.

             Concerning the first part he makes two points. First he sets forth the different species of causes. Secondly, where he says, 'All the causes . . .' (195 a 15), he reduces them to four.

             Concerning the first part he makes two points. First he sets forth the different causes. Secondly, where he says, 'As the word . . .' (195 a 3), he points out certain consequences which follow from the above mentioned diversity.

             178. He says, therefore, first that in one way a cause is said to be that from which something comes to be when it is in it, as bronze is said to be the cause of a statue and silver the cause of a vase. The genera of these things, i.e., the metallic, or the liquifiable, and such things, are also called causes of these same things.

             He adds 'when it is in it' in order to differentiate this cause from the privation and the contrary. For the statue, indeed, comes to be from bronze, which is in the statue when it is made. It also comes to be from the unshaped, which, however, is not in the statue when it is made. Hence bronze is a cause of statue, but the unshaped is not, since it is only a per accidens principle, as was said in Book I.

             179. Secondly a cause is said to be the species and exemplar. This is called a cause insofar as it is the quidditative nature [ratio] of the thing, for this is that through which we know of each thing 'what it is'.

             And as was said above that even the genera of matter are called causes, so also the genera of a species are called causes. And he gives as an example that harmony of music which is called the octave. The form of an octave is a proportion of the double, which is a relation of two to one. For musical harmonies are constituted by the application of numerical proportions to sounds as to matter. And since two or the double is the form of that harmony which is the octave, the genus of two, which is number, is also a cause. Thus just as we say that the form of the octave is that proportion of two to one which is the proportion of the double, so also we can say that the form of the octave is that proportion of two to one which is multiplicity. And so all of the parts which are placed in the definition are reduced to this mode of cause. For the parts of the species are placed in the definition, but not the parts of the matter, as is said in Metaphysics, VII. Nor is this contrary to what was said above about matter being placed in the definitions of natural things. For individual matter is not placed in the definition of the species, but common matter is. Thus flesh and bones are placed in the definition of man, but not this flesh and these bones.

             The nature of the species, therefore, which is constituted of form and common matter, is related as a formal cause to the individual which participates in such a nature, and to this extent it is said that the parts which are placed in the definition pertain to the formal cause.

             It must be noted, however, that he posits two things which pertain to the quiddity of the thing, i.e., the species and the exemplar. For there is a diversity of opinions concerning the essences of things.

             Plato held that the natures of species are certain abstracted forms, which he called exemplars and ideas, and because of this he posited the exemplar or paradigm.

             However those natural philosophers who said something about form placed the forms in matter, and because of this he named them species.

             180. Next he says that that from which there is a beginning of motion or rest is in some way called a cause. Thus one who gives advice is a cause, and the father is a cause of the son, and everything which brings about a change is a cause of that which is changed.

             It must be noted with reference to causes of this sort that there are four kinds of efficient cause, namely, the perfecting, the preparing, the assisting, and the advising causes.

             The perfecting cause is that which gives fulfilment to motion or mutation, as that which introduces the substantial form in generation.

             The preparing or disposing cause is that which renders matter or the subject suitable for its ultimate completion.

             The assisting cause is that which does not operate for its own proper end, but for the end of another.

             The advising cause, which operates in those things which act because of something proposed to them, is that which gives to the agent the form through which it acts. For the agent acts because of something proposed to him through his knowledge, which the advisor has given to him, just as in natural things the generator is said to move the heavy or the light insofar as he gives the form through which they are moved.

             181. Further, he posits a fourth mode of cause. A thing is called a cause as an end. This is that for the sake of which something comes to be, as health is said to be a cause of walking. And this is evident because it answers the proposed question 'why'. For when we ask, 'Why does he walk?', we say, 'That he may become healthy'; and we say this thinking that we assign a cause. And thus he gives more proof that the end is a cause than that the other things are causes, because the end is less evident, inasmuch as it is last in generation.

             And he adds further that all things which are intermediates between the first mover and the ultimate end are in some way ends. Thus the doctor reduces the body in order to produce health, and so health is the end of thinness. But thinness is produced by purgation, and purgation is produced by a drug, and the drug is prepared by instruments. Hence all of these things are in some way ends, for the thinness is the end of the purging, the purging is the end of the drug, and the drug is the end of the instruments, and the instruments are the ends in the operation or in the seeking for the instruments.

             And thus it is clear that these intermediate things differ from each other insofar as some of them are instruments and some of them are operations performed by instruments. And he brings this out lest anyone think that only that which is last is a cause in the sense of 'that for the sake of which'. For the name 'end' seems to refer to something which is last. Thus every end is last, not simply, but in respect to something.

             He finally concludes that this is perhaps all the ways in which the name 'cause' is used. He adds 'perhaps' because of the causes which are per accidens, such as chance and fortune.

             182. Next where he says, 'As the word has . . .' (195 a 3), he makes clear three things which follow from what he has said about the different causes.

             The first point is that since there are many causes, then one and the same thing has many causes per se, and not per accidens. Thus the art of the sculptor is a cause of a statue as an efficient cause, and bronze is a cause as matter. And so it is that many definitions of one thing are sometimes given in accordance with the different causes. But the perfect definition embraces all of the causes.

             The second point is that some things are causes of each other in respect to different species of cause. Thus work is an efficient cause of a good habit, yet a good habit is a final cause of work. For nothing prevents a thing from being prior and posterior to another according to different aspects [ratio]. The end is prior according to reason [ratio], but posterior in existence; the converse is true of the agent. And in like manner, the form is prior to matter in respect to the nature [ratio] of being a complement, but the matter is prior to form in respect to generation and time in everything which is moved from potency to act.

             The third point is that the same thing is, at times, the cause of contraries. Thus through his presence the navigator is the cause of the safety of the ship, through his absence, however, he is a cause of its sinking.

             183. Next where he says, 'All the causes . . .' (195 a 15), he reduces all the causes mentioned above to four species. He says that all the causes enumerated above are reduced to four modes, which are evident. For the elements, i.e., the letters, are causes of syllables, and in like manner earth is a cause of vases, and silver of a vial, and fire and such things, i.e., the simple bodies, are causes of bodies. And in the same way every part is a cause of the whole, and the propositions in a syllogism are a cause of the conclusion. And all of these things are understood as causes in the same way, namely, as that from which something comes to be is called a cause, for this is common to all the instances mentioned above.

             However, of all the things just enumerated some are causes as matter, and some as form, which causes the quiddity of the thing. Thus all parts, such as the elements of syllables, and the four elements of mixed bodies, are causes as matter. But those things which imply a whole or a composition or some species are understood as form. Thus species is referred to the forms of simple things, and the whole and composition are referred to the forms of composites.

             184. But there seems to be two difficulties here.

             The first is the fact that he says that the parts are material causes of the whole, whereas above he reduced the parts of the definition to the formal cause.

             It can be said that he spoke above of the parts of the species which fall in the definition of the whole. But here he speaks of the parts of the matter in whose definition falls the whole. Thus circle falls in the definition of semicircle.

             But it would be better to say that, although the parts of the species which are placed in the definition are related to the supposit of nature as a formal cause, they are, nevertheless, related to the very nature of which they are parts as matter. For all parts are related to the whole as the imperfect to the perfect, which is, indeed, the relation of matter to form.

             Further a difficulty can be raised with reference to what he says about propositions being the matter of conclusions. For matter is in that of which it is the matter. Hence speaking of the material cause above, he said that it is that from which something comes to be when it is in it. But propositions are apart from the conclusion.

             But it must be pointed out that the conclusion is formed from the terms of the propositions. Hence in view of this the propositions are said to be the matter of the conclusion insofar as the terms which are the matter of the propositions are also the matter of the conclusion, although they are not in the same order as they are in the propositions. In this same way flour is called the matter of bread, but not insofar as it stands under the form of flour. And so propositions are better called the matter of the conclusion than conversely. For the terms which are joined in the conclusion are posited separately in the premises. Thus we have two modes of cause.

             185. Some things are called causes for another reason, i.e., because they are a principle of motion and rest. And in this way the seed which is active in generation is called a cause. Likewise the doctor is called a cause of health according to this mode; so also the adviser is a cause according to this mode, and everyone who makes something.

             Another text has 'and propositions'. For although propositions, insofar as their terms are concerned, are the matter of the conclusion, as was said above, nevertheless insofar as their inferential power is concerned, they are reduced to this genus of cause. For the principle of the discourse of reason to its conclusion is from propositions.

             186. Another meaning of cause is found in other causes, i.e., insofar as the end or the good has the nature [ratio] of a cause. And this species of cause is the most powerful of all the causes, for the final cause is the cause of the other causes. It is clear that the agent acts for the sake of the end. And likewise it was shown above in regard to artificial things that the form is ordered to use as to an end, and matter is ordered to form as to an end. And to this extent the end is called the cause of causes.

             Now since he has said that this species of cause has the nature of a good, while sometimes in those things which act by choice it happens that the end is evil, he forestalls this difficulty by saying that it makes no difference whether the final cause is a true or an apparent good. For what appears good does not move except under the aspect [ratio] of good.

             And thus he finally concludes that the species of cause are as many as were mentioned.