The Cartesian Gulf
It is a frequently heard complaint that Descartes divided matter from mind, leaving it impossible to comprehend how the two, being so different, could interact. One aspect of his claim was that matter is allegedly spatial, while mind is non-spatial. He was however (as Princess Elizabeth of Bohemia told him at the time) quite wrong about the non-spatiality of the mind. The mind is certainly non-spatial in some respects, but spatial in others. It must be so, otherwise we could not understand spatiality, ‘see’ or ‘grasp’ it with our consciously observing eyes and minds, be able to measure it in the world around us. Probably also we could not have invented (or should it be ‘discovered’?) mathematics. After all, we see space all around us: as Kant pointed out, it’s one of the fundamental categories of our understanding. This could not be so unless our consciousnesses were in part spatial.
But where is the mental space which our thoughts, feelings and sensations inhabit? It’s certainly not to be found in the scientist’s physical world-space. So where is it? A part of the answer may be that this question is the wrong way round. We can ask where the separate parts of our experience are vis-à-vis our phenomenal field, but we cannot ask where the latter is. The mind is not located; it locates. For it is quite plain that our conscious experience locates the elements of the phenomenal field (including our own bodies) in relation to itself. In this respect the mind is like the Universe. This too has no location: space, time and whereness are all within it. Subject also to the same presumption, the Universe too, like consciousness, has an inside but no outside.
That mind is partially spatial, however, just might help the problem about how mind and matter interact.
The Question of Time
The question of location leads to that of temporal location. As has often been noted, there is an intimate – perhaps an exclusive – relationship between consciousness and time. No ‘time-force’ has yet been discovered in the natural world by science, and hence the forward flow of time is (so far) inexplicable in terms of physics and sensible only in terms of our conscious experience. Thus we may read:
The laws of Newtonian mechanics and electromagnetic theory are indifferent to the direction of time. If at a certain instant we were to reverse all the velocities of all the constituents of a Newtonian system, the system would proceed to ‘unwind’ and run backwards, and would be in exactly the same position at date t after the reversal as it had been at the date -t before reversal. If we were shown a film of a Newtonian system we could not tell whether the film was being run forwards or backwards. This contrasts [...] with films of human activities, biological processes or the phenomena of thermodynamics. If we see men walking backwards, or plants growing smaller and smaller and contracting into seeds, or a cup of warm tea separating itself into hot raw tea and cold milk, we know that we are seeing the film the wrong way round. But if we saw the planets all going backwards in elliptical orbits, there would be nothing to indicate that anything was amiss. [...] There is no direction of time implicit in Newtonian mechanics, as there is in human activity, in biological process or in thermodynamics.
Yet time in Einstein’s system is one of the basic dimensions of the Universe. And without that forward flow, an apparent nonsense is made of the Universe’s past and future history, namely its existence in the form of events.
Given the apparent absence of a ‘time-force’ from the world as seen by science, it has (rather naturally) been suggested that we inhabit a ‘block Universe’, in which everything is determined in advance from beginning to end. In this case, time would be one of the dimensions, but its whole extent would be entirely determined in advance – like the motionless All of Parmenides and Zeno. There would then be no longer any sense to ‘before’ and ‘after’, and movement in time would be non-existent – except that living creatures, pinned by their consciousness to a moving but always present moment, would traverse time, experiencing the ‘illusion’ of living through time from past to future.
So much for the deterministic picture favoured by some scientists and philosophers. However, if we compare the dimension of time (as experienced by living beings) to the three spatial dimensions, we find that unlike them it is monodirectional. In all spatial dimensions one can travel freely in both directions; in time alone is one confined to a single direction, from past to future. Moreover, although the other dimensions allow motion in two directions, time compels motion in only one direction. There is a directional lock. On account of this feature, I shall refer to time as being a half dimension. The past already exists and appears unchangeable; the future is as yet fluid, uncertain, unknown, the realm of possibility not of immutability.
It is evident that, without this uncertainty of the future (dependent on the ‘half-dimensional’ nature of time), one of the most important elements of our experience could not exist even as a possibility. For, if events are to occur in the true sense of events, i.e. as choices between alternatives, then it is clear that we cannot live in a block universe. A universe which provides either free will or its semblance must necessarily permit the future to be as yet uncertain. In that case, necessarily, our consciousnesses are important for a double reason: as (1) the criteria of ‘before’ and ‘after’ and as (2) the vehicles of choice between alternative outcomes, these two features being mutually dependent.
The special link of time with consciousness thus appears to be important at a profound level. Consciousness is intimately locked together with time, which is one of the fundamental dimensions of the Universe itself. Now of course, as is universally recognized, questions of meaning or purpose are outside the remit of science. No matter: this is a metaphysical question, not a scientific one. Here we have the suggestion that, as far as time is concerned, the Universe itself is set up in such a way as to permit consciousness to act meaningfully and purposefully. This feature of the Universe must surely be incomprehensible to the materialist / determinist, and in this respect it resembles Priest’s question (quoted above) as to why the created Universe contains subjectivity at all. In an entirely material Universe, (1) subjectivity and (2) the half-dimensionality of time are both superfluous to the point of incomprehensibility. All this suggests, once again, that consciousness is a fundamental element of the Universe we actually inhabit.