The three chapters 26 - a little labored, it may seem - which Aristotle devotes to the study of chance are a logical sequence to the search for the kinds of causes. Some things, we commonly say, happen (that is, are caused) by chance. Are we to conclude that chance and fortune are separate kinds of causes, distinct from the ones we have just considered? This is the question Aristotle proceeds to answer, examining the views of others and then stating his own.
1. Theories Criticized by Aristotle 27
Aristotle begins by observing that some deny the very existence of chance. Every event, they say, has its proper cause. If, for example, I should meet at the market a man whom I really wanted to see but whom I had not gone there to find, I may well credit the meeting to chance. But was it chance? No, says the opposition. There was a definite cause of the meeting, namely, the intention I had to go and buy in the market. Similarly in all cases attributed to chance or fortune it is possible, they maintain, to find a proper cause at work - an interpretation, it need hardly be said, that runs counter to the popular mind.
Others - the Atomists - ascribe the formation of the heavens, in fact of all the worlds, to chance.28 Thus, what would seem to be the most regular occurrences in nature - the celestial movements - are due to chance. Yet in the area where we most often come upon exceptions to the regular course of events, in the generation or production of things around us, in the history of men and animals and plants, in this area these same people (the Atomists) deny all chance and say that everything happens from fixed causes. This, suggests Aristotle in rebuttal, is a strange statement to make, for one should have expected just the reverse.29
2. Aristotle's Definition of Chance
In Aristotle's view the first mark of chance is infrequency. What always happens, semper, or most of the time, ut in pluribus, is evidently the effect of causes acting in their proper nature or capacity. But what seldom happens, ut in paucioribus, and comes as an exception, this seems to escape the determining influence of these causes.
Infrequency, however, as Aristotle makes clear, is not enough to indicate that chance is at work. The event must belong to the order of finality, something that could be an object of choice. But though the event could have been purposely sought, it was not sought. So, to come back to our example, when a creditor just happens to meet his debtor in the market place, it is a chance meeting. Neither, assumedly, went to meet the other, nor do they always meet there. But, and this is the point, the encounter could have been premeditated, or knowingly sought. The fact is it wasn't.
These three notes of chance - "exceptional," "intentional," but "not intended" - are readily discernible in this definition of Aristotle's, namely, "Fortune and chance are incidental (per accidens) causes in regard to things which admit of coming to pass neither absolutely nor for the most part, and which, moreover, can come to pass in view of an end." 30 St. Thomas transcribes Aristotle as follows:
Utrumque, scilicet fortuna et causa, est causa per accidens; et utrumque est in its quae contingunt non simpliciter, id est semper, neque frequenter; et utrumque est in its quae fiunt propter aliquid.31
Though the definition applies both to fortune (τυχη) and chance (αυτοματον), Aristotle makes a distinction between them. Chance is the generic term, including all cases, but when chance bears on creatures who have freedom of choice, it is called fortune. If the unexpected is favorable, it is good fortune; if unfavorable, ill fortune. A lucky creditor is the object of good fortune, an unlucky one, of ill fortune. A nonliving thing, or even an animal - yes, a babe in arms - is not said to be similarly blest or plagued.
3. Import of Aristotle's Theory
What did Aristotle have in mind with his theory of chance? Obviously, he meant to oppose the idea of absolute determinism in nature, that the same causes invariably produce the same effects. Hence his insistence on what most men would never think to question, namely, that some facts and events are not only rare but exceptional. Yet these facts have a kind of cause, and Aristotle's further aim is to show that they pertain to the order of final causality. The conclusion that follows from this is that a philosophy, a meaningful explanation, of chance is possible but only if it is based on a philosophy of order or regularity. Indeterminism in nature presupposes a certain determinism. Were there no normals, there would be no abnormals. This, in a word, is the basic import of Aristotle's theory of chance.
Still, it may be asked whether chance, as defined above, is the only source of contingency in nature. A careful reading of all the pertinent passages would show that Aristotle's thought is more involved than might appear from isolated paragraphs. Chance, we should find, often denotes exceptional facts of any kind, including such as might not have been produced in view of an end.32
Another point of interest is how the purpose-associated working of chance ties with the necessary action of matter, or, in the more usual phrase, with material necessity. Of this necessity, though not explicitly of this problem, we shall speak in a moment.