Does the mind need the brain in order to function? Can there be such things as disembodied minds? Can minds exist without matter?
According to Buddhist process philosophy, there is no logical reason why not...
Process Philosophy and the Mind
Process philosophers claim that processes, rather than things or substances, are at the basis of reality. There are no basic building blocks of the world, because when those potential building blocks are examined in sufficient detail, they are all found to be processes rather than things (they are dynamic wave-functions which only behave as particles under specially constrained circumstances).
Similarly, minds are not ‘things’, they are processes. Buddhist meditators claim that the mind is a continuous process which is subtly conscious even in the deepest dreamless sleep. According to Buddhist teachings, the mind is also conscious after death (‘for in that sleep of death, what dreams may come, when we have shuffled off this mortal coil…’)
Two Types of Process - Mechanistic and Mental
According to process philosophy, there are two types of processes in the universe - mechanistic and mental. This view is known as ‘process dualism’ and should be carefully distinguished from Cartesian ‘substance dualism’, which believes in a body which is inhabited by a soul.
Mechanistic processes are those that can be modelled by a Turing machine, or combination of Turing machines (such as the instruction-set of a computer). Mechanistic processes include all the laws of physics (see the Church-Turing-Deutsch Principle), plus any algorithms you care to mention, whether they correspond to anything physical or not.
Mental processes are those that cannot be modelled by Turing machines or computers, and consist of subjective phenomena known as ‘qualia’ (qualitative experiences such suffering and pleasure) and ‘intentionality’ (meaning, attention, ‘aboutness’ and semantics), plus possibly also some intuitive mathematical perceptions such as Gödel’s Theorem).
The Hard Problem
Although mechanistic and mental processes interact in the brain and are obviously closely correlated, there is no known mechanism (and maybe there is no possible mechanism) for physical events in the brain to produce mental events (this mystery is known in the trade as ‘The Explanatory Gap and/or ‘The Hard Problem’).
Buddhist philosophers claim that the mind is a permanently active process rather than a passive recipient of neural events, and has to actively observe changes of neural states to turn them into mental experiences. The mind is said to ‘go to’ its object.
This is given credence by the fact that although is seems impossible to envisage any mechanism for the neural events to produce mental events, the converse is not the case. A plausible (though admittedly controversial) mechanism known as the Quantum Zeno Effect has been proposed for interfacing mental attention (an aspect of intentionality) with neural firings.
So, in any contest for ontological primacy between the mental and the physical, it could be that the mental has a slight advantage. But anyway, let's not go there in this particular post. Let's just accept that mental and physical processes are different but equal, though both types have ontological primacy over 'things', substances and material appearances (which are all reducible to processes).
Disembodied Physical Processes.
Nowadays we know that disembodied processes can exist and operate in the physical world. These are processes with no need for supporting matter, medium or substrates. They are standalone processes that do their things with no visible means of support.
The first such disembodied process was identified in 1887 by Michaelson and Morley, who proved that the luminiferous (‘light-bearing’) aether simply did not exist. This came as a shock to the Victorians. After all, light was known to be a process of oscillating waves, and waves had to propagate through some sort of medium like the waves on the sea, or sound waves through the air.
The acceptance of independently functioning processes caused a major rethink of classical physics and led to the Theory of Relativity.
Another even worse surprise came when it was found that particles of matter, when examined carefully at a small enough scale, also behaved as waves, and interfered with each other and even with themselves. But waves travelling through what? They couldn’t possibly be propagating through matter, because they were matter!
Consequently, all notions of matter being a fundamental aspect of the world disappeared from physics by mid twentieth century, and process metaphysics ruled supreme.
Equal Opportunities for Mental Processes!
So, if physical processes can operate in the complete absence of any material basis, substrate, medium or means of support, then why shouldn’t mental processes be able to do the same? I appreciate this is an argument from analogy, with the use of Occam's razor ("entities must not be multiplied beyond necessity") to cut down the superfluous ontological apparatus of an unnecessary substrate, but it does demonstrate that there’s no logical reason that mental processes need to be embodied in matter (e.g. brains) in order to continue to function. Indeed, recent evidence suggests that mental activity may continue when the brain has shut down.
If the brain shuts down permanently, then the mental continuum (the root mind) may have to wander off and find another brain to associate with. As the Buddhist philosopher and computer pioneer Alan Turing said "When the body dies, the 'mechanism' of the body holding the spirit is gone, and the spirit finds a new body sooner or later, perhaps immediately."