The major psychological concept of thinking is the 'cognitive model', which states that thinking is a kind of information processing done by the brain: let us call this model Brain-Thinking.
Brain-Thinking is an automatic, computer-like processing that has either been learnt, or else is instinctive (i.e. built-in by natural selection, on the basis of evolutionary history).
But reflection informs us that Brain-Thinking is a model; and being a model it necessarily leaves-out a great deal, consequently is partial and distorted. Furthermore, if Brain-Thinking has validity, the theory cannot itself be merely a consequence of Brain-Thinking - because Brain-Thinking is merely a consequence of learning experience or selection for whatever is reproductively-expedient.
If thinking is to be potentially valid (as I am assuming) then thinking needs to be true; and to be true the thinking process must be directly tied-to reality - without any steps in between where there may be errors or misunderstandings of communication.
In other words, thinking needs to be reality.
In other words, thinking cannot - ultimately - be regarded as merely 'thinking-about, nor 'a-picture-of reality', nor any kind of secondary 'representation' of reality - because any picturing/ representing process is uncertain.
For instance, if thinking is supposed to be derived from perceptions, then there are errors and distortions of the perceptual apparatus and of the stages of processing of raw perceptions into comprehensible representations - all of which detach thinking from reality. Or if thinking is derived from memories, then there are all the problems of making a representation from sensory perception, plus all the processes by which memories are made, stored, located and read...
No - for thinking to be valid, thinking needs to be actually real in-and-of-itself, unmediated, directly.
In sum, thinking must itself be reality - at least potentially. But clearly this cannot be the base for Brain-Thinking, as it is understood by Psychology - brain thinking is not regarded as itself-reality, but at most about-reality.
If Brain-Thinking is an automatic process - causally-determined and therefore without possibility of 'freedom' or 'agency' or genuine creativity; then Mind-Thinking is (by contrast) conscious, willed or purposive, creative and free.
A Mind-Thinking capable of being understood as actual reality therefore needs to be conceptualised as qualitatively different from Brain-Thinking. If Mind-Thinking is reality it cannot be a material process - therefore it must be immaterial; it cannot be 'in' the brain - because reality cannot be subjective/ unique to one person - therefore must be objective/ accessible to many persons, simultaneously.
Indeed, Mind-Thinking needs to be reality itself which is not merely 'accessible' but itself the world of reality in which our own personal thinking participates. Thus, as we think, we are actually engaged-with and participating-in reality as it unfolds.
In other words, with Mind-Thinking, any single person thinking is actively engaged in making reality - objective, permanent, universal reality - as well as knowing reality.
This is only apparent if we become aware of the nature, constraints and limitations of the mainstream psychological model of thinking; and take accounts of the pre-requisites of valid thinking.
Of course, we might try to contend that thinking is not valid, but is arbitrary and unlinked with reality; but then this would undermine the thinking which contends it, since it rules-out any possibility of validity in the thinking which led to the contention that thinking is invalid.
If thinking is indeed non-valid, and has no necessary relation to reality; then there is nothing to be said - nothing to be said about anything...