Elements of metaphysics

by A. E. Taylor

The “natural view of the world” unhesitatingly accepts these cases as instances of interaction or Transeunt Causality on exactly the same level as the origination of change of state in one body by change in another, and Descartes himself had acquiesced in this interpretation. But such a view, as his successors saw, is quite incompatible with the alleged disparateness and independence of the two orders of existence, the bodily and the mental. Geulincx and Malebranche accordingly took refuge in the doctrine that the interaction is only apparent. In reality there is a complete solution of continuity wherever the series of changes in the one order terminates and that in the other begins. What really happens, they taught, is that God adapts the one series to the other. On the occurrence of the bodily stimulus, God intervenes to produce the sensation or emotion which is required to harmonise our action with our environment. Similarly, on the occurrence of a volition, God interferes to set the corresponding movement going in our bodily organism.

Thus the change in the one order is merely an occasion for the intervention of God, who is the actual cause of the corresponding change in the other. Within each order the series of changes once initiated are then supposed to be causally connected. The divine interference only comes in where the two orders come into contact. Berkeley adopted half of this doctrine without the complementary half. Inasmuch as, according to him, physical or non-mental things are mere complexes of presentations, or, in his own terminology, “ideas,” and ideas are purely inert, the real cause of every sensation must be God, who thus directly intervenes to give us an indication of the further sensations we shall receive according to the action we take on the present presentation. Transeunt Causality in the reverse direction, the immediate origination of bodily movement by volition, Berkeley seems to have admitted without criticism as a self-evident fact.[^[113]]

It will not be necessary here to discuss the half-hearted version of Occasionalism adopted by Berkeley. It is clear that the admission of direct origination of bodily change by mental cannot be consistently combined with the denial of all Transeunt Causality in the reverse direction. If all physical existence, my own body included, is nothing more than an inert complex of presentations, it is just as hard to see how it can be the recipient of mentally originated change as to see how it can originate mental change. What is not in any sense active cannot be passive, for passivity is simply repressed and thwarted activity.

We confine ourselves, then, to Occasionalism of the thorough-going type. Now, against such Occasionalism there is the obvious objection that it transforms the whole course of our existence into one long succession of miracles, a point upon which Leibnitz is fond of insisting in his criticisms of Malebranche. And the doctrine is not really consistent with itself for two reasons. (1) It is clear that, according to any possible definition of Causation, the doctrine of Occasionalism involves causal interaction between God on the one hand and both the supposedly disparate orders of reality on the other. Changes in either order definitely determine the intervention of God to originate definitely determined changes in the other order. Thus God’s internal determinations are at once causes and effects of changes in either order. But if, e.g., a material change of state can be the cause of a determination in God, the whole basis of the denial that a change in the material order can originate change in another order of reality, is swept away. The net result of the theory is simply to re-establish the transeunt action of the two orders on each other by means of a roundabout circuit through the mind of God.

What Geulincx and Malebranche really had in mind was the simple reflection that we cannot tell how a physical change can bring about a mental change, or vice versâ.[^[114]] But this problem is not advanced in the least by introducing God as a third factor. How a change in the one order can bring about a determination in the mind of God, and how again God brings about the corresponding change in the other order, are simply two insoluble problems of the same kind as that they were intended to explain. After the introduction of God as third factor in the causal process, the fact still remains as before, that certain definite changes in the one order ensue upon definite changes in the other, and this is precisely the fact which is denoted by the name of Transeunt Causality.

Of course the problem would alter its character if God were conceived as another expression for the total system of Reality. The doctrine of Occasionalism would then become simply a statement of the view that no two things are really independent, and that it is in virtue of their inclusion in a larger systematic whole that what we call separate things can influence each other. But, in spite of numerous passing utterances which point to this view, it is quite certain that Occasionalism was seriously intended by its authors as a solution of the problem of Causality on strictly traditional theistic lines.

(2) A second defect of the doctrine lies in the failure of its originators to extend it to all cases of causal relation. It is a mere prejudice when Geulincx and Malebranche allow themselves to assume that the sequence of physical change on preceding physical change, or mental change on preceding mental change, is more self-explanatory than the sequence of a mental change on a physical. In both cases we can ascertain that one state definitely follows a previous one; in neither can we answer the ultimately unmeaning question, by what machinery this sequence is brought about. For any answer must obviously consist in the interpolation of an intermediate link, and with regard to the production of this intermediate link the same question arises, and thus we come to the indefinite regress, the invariable indication that we have been asking an unmeaning question.

(b) The Pre-established Harmony. More philosophical was the attempt of Leibnitz to reconcile Pluralism with the apparent interaction of things. According to Leibnitz, every ultimately real thing or monad is a self-contained whole; it contains, therefore, in itself the ground of the sequence of its own states. Hence there can be no real origination of change in one monad by the occurrence of change in another. The life of every monad must consist purely in the development of its own internal nature. As Leibnitz phrases it, there are no windows in the monads through which states and qualities can fly from one to another. Yet some account must be taken of the apparent fact that, since the world of experience is not a chaos, the changes in one thing seem to be connected by definite law with the changes in others.

Now, according to Leibnitz, this apparent interaction can only be accounted for, if we decline to tolerate the perpetual miracle of Occasionalism, by the theory of a Pre-established Harmony between monads. If the whole of the independent monads are of such a nature that each, while actually following the law of its own development, behaves in the way required by the internal development of all the rest, then, though each is really self-contained, there will be the appearance of interaction. Leibnitz illustrates the possibility of such a harmony by the case of two clocks which keep time with each other, without either the actual regulation of the one by the other, or the maintenance of a connection between them, simply because each is properly constructed; and again, by the case of a number of musicians playing from the same music but concealed from each other’s observation, who keep time and tune simply because each is playing his own score correctly.

Probably this is the most satisfactory hypothesis which can be devised for the conciliation of apparent interaction with a radical Pluralism. But its logical defects are apparent on the face of it. When we ask to what the harmony between the internal states of the several monads is ultimately due, Leibnitz hesitates between two answers. It is due, according to one account, to the choice of God, who in His wisdom saw fit to establish the best of all the possible worlds. But at the same time it was God’s recognition of the harmony between the monads of this special world-system which led Him to give it the preference over other antecedently possible systems, and to bring it rather than any other from mere possibility into actual existence.