I am simply 'testing' this argument.

But I take it that simplicity is an epistemic virtue and that other things being equal, we have reason to think the simplest theory about reality that explains all the data is the correct one.

To suppose that there exists a mind and its own mental states is a very simple thesis, for not only is one kind of thing - a mind - supposed to exist, but only one of it is supposed to exist too.

I will suppose, then, that this is the sum total of what exists and see if, by making such assumptions, the job of explaining everything else can be done.

Assume that at first the mind is in random mental states - random sensations and thoughts occur in it. Over enough time a desire to look for patterns will arise and over enough time the thought that 'that which exhibits a pattern is default real' will arise too and will arise at the same time as the desire to look for patterns. And over enough time those two mental states will arise at the same time as two or more sensations - quite by luck - seem to exhibit a pattern. Yes, the odds will be vanishingly tiny - but that doesn't matter. It'll happen eventually. I take myself currently to be 'in reality' for about 16-18 hours at a go, but the first 'glimpse' would have been for a fraction of a second. It would have built, though....like a crystal.

At this point the mind in question will take those sensations to be of a reality and all others to be a dream it is having (which is what we mean by a dream - sensational experiences that we do not consider to be of reality but wholly a product of our own mind). When another sensation arises within the bubbling soup of sensations that seems to cohere with the sensations that the mind took to be of reality, that sensation will also be taken to be of reality and not part of the dreamscape.

Over enough time, the mind will sift those experiences that seem to exhibit a pattern and to cohere with previous experiences and call that set 'reality' (and it will just build indefinitely), and the others will be considered 'dream'.

So, is that possibly the situation we - I - am in? Those sensational experiences that are adaptive - that fit with the pattern I am looking for - will get selected for by my mind as parts of 'reality', whereas those that do not will be deemed dream.

I now take myself to have been in reality - in and out - for about 50 years. This will go on and on as, with enough time, more and more experiences arise that are adaptive - that is, that fit with the evolving narrative (all others continuing to be considered 'dream').

Interesting implication: we (I) will never die. We (I) will just get the impression we have been in reality for longer and longer and longer. You will experience death-like events. But those will be folded into the dreamscape and not considered part of reality. You will only consider those experiences taht continue the story to be reality. And so the story is going to be neverending.

And when we - I - sleep, it may be for trillions of years....eventually a sequence of experiences and thoughts will arise that replicate sufficiently those I had that I considered reality and that continue it....and that will be taken to be the point I awake. And on and on it goes.

it can be noted as well that once the crystal starts to form, it may affect the random flow of thoughts and other sensations, aiding its own building. that is, thoughts and sensations that tend to cause sensations and thoughts that cohere with them will be selected for (where 'selected for' just means 'considered part of reality').

What I have described is just evolution by natural selection, except that it is applied at the level of a mind's sensations, and 'not being selected for' is just a matter of something being considered dream rather than reality. Does the job, does it not?

And this thesis is simpler than supposing that there exists a mind-external physical reality in which evolution by natural selection is occurring.