If mental events are to be caused by physical events, physical events must succeed one another within a temporal context. That is to say, physical states must occur in temporal succession where event #1 occurs first followed by event #2, then by event #3, etc.--all within the context of a continuous time flow. It is logically impossible to define/describe cause-effect relationships outside such a context of an explicit time flow.
The physical structures of brain and body are part of spacetime. And like all of physical reality, these structures exist in a static, block-like fashion. Spacetime, which includes matter/energy within it, exists in its totality--in an "all-at-once" fashion. By definition, geometric time cannot, and does not flow.
However, subjective/"mental" time (i.e., "mental life") does flow. Here we see scientific materialism falter: given the static/spatial and "all-at-once" character of physical reality, materialism cannot logically account for or accommodate the dynamic nature of subjective mental existence.
Clearly we must abandon the notion that mind is physical and part of physical reality. Mind is necessarily non-physical.
As explained above, in the absence of an explicit time flow, one cannot define cause-effect relationships. Since states of mind cannot, by definition, be causally dependent upon states of matter, it is apparent that there really is no such thing as a "mind/body problem."
A consistent description of reality is possible only if we abandon the notion of a mind-independent reality; we must recognize subjective experience for what it is: the only context within which physical reality can possibly exist. There can be no concrete reality outside the subjective experiences of individual minds.
"Scientific objectivity," however, is retained in my approach. The subjective experiences of individual minds (observed experimental data, in particular) of course lend themselves to mathematical description. In addition, the similarities in our experiences of physical reality strongly suggest that an objective, potential reality exists. The concrete, observed, phenomenal reality of conscious experience, however, must necessarily remain entirely subjective.
This becomes easier to understand when we consider the nature of the "present moment of time."
What is "the present"? It is a non-physical context within which physical reality exists; this "non-physical context" encompasses the entire perceived physical world. The reader must recognize, however, that this "present moment of time" is an entirely subjective phenomenon!
In fact, the simplest and most compelling explanation of the present is that it is consciousness/conscious experience. Contrary to what we generally assume, the present moment is not "a phenomenon experienced by consciousness": it is, rather, conscious experience itself!
To better understand this the reader should appreciate that we cannot accommodate the notion of an objective present within spacetime. Relativity essentially defines all spacetime points as existing "all-at-once." By definition, this physical structure of spacetime does not flow; it cannot accommodate the notion of an objective, moving present. This point is emphasized in the writings of physicists such as Paul Davies and Roger Penrose. Penrose writes:
...I suggest that we may actually be going badly wrong when we apply the usual physical rules for time when we consider consciousness! There is, indeed, something very odd about the way that time actually enters into our conscious perceptions in any case, and I think that it is possible that a very different conception may be required when we try to place conscious perceptions into a conventionally time-ordered framework. Consciousness is, after all, the one phenomenon that we know of, according to which time needs to 'flow' at all! The way in which time is treated in modern physics is not essentially different from the way in which space is treated* [see below] and the 'time' of physical descriptions does not really 'flow' at all; we just have a static-looking fixed 'space-time' in which the events of our universe are laid out!...
[*This symmetry between time and space would be even more striking for a two dimensional space-time. The equations of two-dimensional space-time physics would be essentially symmetrical with respect to the interchange of space with time--yet nobody would take space to 'flow' in two-dimensional physics. It is hard to believe that what makes time 'actually flow' in our experiences of the physical world we know is merely the asymmetry between the number of space dimensions (3) and time dimensions (1) that our space-time happens to have.]
(Roger Penrose, The Emperor's New Mind [Oxford: Oxford University Press, 1989], 443-444)
Finally, since conscious experience constitutes "the present," we conclude that there must be as many presents as there are minds. These individual presents, however, do not bear a temporal relation to each other. If we try to coordinate these presents/minds with each other temporally, we assume that they are embedded within some "super-present"--i.e., within an objective present which encompasses all individual minds. (Only such a present can enable such temporal coordination). However, as already explained, an objective present cannot exist, by definition.
...Individual minds are properly regarded as "monads"--"detached" and "isolated" from one another in a very deep and fundamental sense.
In wrapping-up this post, I stress that the conclusions drawn above regarding subjective experience and physical reality are logically inevitable--they are inescapable given the peculiar nature of the "present moment" and the character of spacetime. I suggest that it is only this radically idealistic stance that can ever hope to offer an internally consistent solution to the mind/body problem.Adhanom Andemicael