Third Presupposition The Eliminative Method

Aquinas's answer to that question is the third and last presupposition provided in chapter 14. 'We have a kind of knowledge of' the first being, he says, 'by discerning what it is not, and we come closer to a knowledge of it to the extent to which we can through our intellect eliminate more [characteristics] from it; for the more fully we observe anything's differences from other things, the more end p.91

completely do we discern it' (14.117). And, of course, he's right. Negative discoveries do carve out affirmative information. Just think of the assured progress you'd be making in a game of Twenty Questions by getting nothing but negative answers to your cleverly framed series of questions. 'For example, if we say that God is not an accident'—that is, doesn't belong in any of the nine categories of accident—'he is on that basis distinguished from all accidents.'Therefore, if God can be fitted into the Aristotelian categories at all, he belongs in the first category: substance. 'If we then add that he is not a body, we will distinguish him also from some substances' in the first category, and we will know that God is an incorporeal substance, if he is a substance at all (14.118). And so on.

So the third of chapter 14's presuppositions is methodological, and Aquinas himself calls this indirect route to cognition 'the eliminative method (via remotionis)' (14.117, 119). It is, I think, exactly suited to the project of acquiring cognition of the characteristics of the hypothetical Alpha, coming 'closer to a knowledge of it to the extent to which we can through our intellect eliminate more [characteristics] from it'. That's why Aquinas introduces as his new starting-point only the already accomplished elimination of the characteristic of being in any way subject to change: 'Therefore, in order to proceed by the eliminative method as regards the cognition of God, let us take as a starting-point that which is already manifest from the above [arguments]—I mean, that God is altogether immovable' (14.119).

It may be reassuring as regards the further development of this natural theology to point ahead to two facts about the eliminative method that will emerge as we go on. First, it's not the only method Aquinas uses in building up an indirect cognition of the nature of ultimate reality. After he's prepared the ground with a series of eliminative moves, through chapter 28, he begins to argue in a different way for a special sort of affirmative conclusion, as we'll see in Chapter Five.

Second, the entirely negative and presumably meagre results of the eliminative method are not his only resource even in these early chapters. In applying the method (and indeed throughout SCG) Aquinas freely introduces as premisses of his arguments not only propositions he has argued for earlier but also many propositions he treats as principles of this subordinate science, as needing no support within this project itself. It's not hard to pick out more than end p.92


© Copyright Oxford University Press, 2006. All Rights Reserved ninety such principles in chapters 14-28, for instance. Some of them would be certified as axiomatic by anyone's philosophical intuition—e.g. 'What doesn't exist can't accomplish anything'; 'Parts are incomplete in respect of their whole'; 'A continuum is potentially divisible ad infinitum'. Many others should be readily accepted in these circumstances as Aristotelian commonplaces—e.g. 'Every definition is made up of a genus and differentiae'; 'What is common to many things is something over and above those many only conceptually'. A few of these principles would be hard or impossible for most of us to accept—e.g. 'Intellect is not a corporeal power'. But Aquinas's procedure in SCG typically involves such a proliferation of arguments for each conclusion important to his project that we're seldom, if ever, forced to choose between accepting an implausible principle and bypassing an important conclusion.

Where does Aquinas get these principles? Almost entirely from Aristotle, of course, although his explicit attributions are rare and seem to have been reserved for theses Aquinas probably takes to be distinctively Aristotelian, such as Time is the measure of motion' and There is no infinite magnitude'. And what entitles him to use them as unsupported premisses? No doubt he takes some of them to be self-evidently true, and surely he's sometimes within his rights to do so—e.g. 'A conditional proposition with an impossible antecedent can be true', or 'Substance does not depend on accident, although accident depends on substance'. I believe that he takes all the others to have been successfully argued for by Aristotle. For instance, when he invokes the Aristotelian thesis of the incorporeality of the human intellect, he justifies doing so by pointing out that 7t has been proved that intellect is

not a corporeal power' (20.183).

12 [P]robatum est quod intellectus non est virtus corporea, which Peg is translates: 'we have proved that the intellect is not a corporeal power' (1975: 113; emphasis added), thereby misleadingly implying that such a proof is to be looked for in the preceding chapters of SCG I.

Nothing of the sort has been even discussed in the preceding chapters of SCG, so his claim that it has been proved must be an allusion to Aristotle's own arguments to that effect in De anima III (an allusion of a sort that his thirteenth-century academic contemporaries would have had no trouble picking up). But since the natural theology Aquinas is developing evidently has, by his own lights, the status of a science subordinate to metaphysics end p.93


© Copyright Oxford University Press, 2006. All Rights Reserved proper, to Aristotelian metaphysics, there's every reason why he should—indeed, must—help himself to Aristotelian principles and argued theses in developing his subordinate science. Still, in assessing any of his arguments, we will of course have to ask about the acceptability of his apparently unsupported premisses.

Drawing on the arguments of chapter 13 for no more about the first cause initially than that it must not be subject to any change, Aquinas carries his investigation of its nature forward by applying the eliminative method again and again in chapters 15-28, arguing for the elimination of at least nineteen characteristics that an altogether immutable first cause couldn't have. In doing so, he regularly draws on propositions of that sort that were argued for earlier (as well as on the Aristotelian principles I've just been talking about). I'll examine several of those derivations and their results in Chapter Four. For my present purposes a look at his very first arguments in this series will be helpful.

For instance, Aquinas's opening move in chapter 15 is to show that anything 'altogether immutable', regardless of any causal function it might have, would also have to be beginningless and endless, since, as he says, 'everything that does begin or cease to exist undergoes it through motion or change' (15.121). Immutability's incompatibility with ceasing to exist is more obvious than its incompatibility with beginning to exist. Still, even though a thing's beginning to exist can't count as a change in that thing, which didn't exist until then, it must count as a change in the way the world is. And so Alpha, which is by hypothesis the ultimate explanation of all change and of the way the world is, could never have begun to exist any more than it could

ever cease to exist.

13 The argument in 15.123 is perhaps clearer than the one in 15.121 as regards beginninglessness, but I think that it's less clear as regards endlessness, and that the argument to the same conclusion in 15.121 is generally the better of the two.

But, as Aquinas goes on to observe in that same chapter 15, the world that Alpha is supposed to be the explanation of is full of things that do, and therefore can, begin and cease to exist. On the basis of that observation he develops another argument, one that focuses on Alpha's causality as the earlier argument focused on its immutability. As we'll see just below, he presents this argument simply as another application of the eliminative method, not as an argument for the existence of anything. But I think that part of it end p.94


© Copyright Oxford University Press, 2006. All Rights Reserved can and should be considered as an argument for Alpha's existence, and that's how I will now consider it. The part I'm interested in I'll call argument G6.

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