The proof for premise 1, is according to you, "it appears to be" which, despite it being couched in a hedge, is easy to confirm through personal experience: I'm aware of my mental processes and also that I exist, distinct from others and actually consider myself to be quite like the driver of a vehicle, steering the body to do my bidding. Also, as you said, there's no sense in which I could talk of a half or a quarter of my mind. — TheMadFool
It is not a 'proof', but 'evidence'. Appearances, whether sensible or rational, are prima facie evidence of the reality of what they represent to be the case. That's a principle of intellectual inquiry without which you'd be unable to argue for anything at all. For instance, it is on the basis of rational appearances that we recognise this argument form:
1. P
2. If P then Q
3. Therefore Q
to be valid.
Our reason represents us to be indivisible, which is prima facie evidence that we are. That 'prima facie' means not that it is a proof - we could discover that we have more powerful prima facie reason to discount these particular rational appearances (not 'all' rational appearances - that'd be self-undermining - but 'these' rational appearances). But it means that the burden of proof is on the person who wishes to deny that premise - they have to provide apparent countervailing evidence, otherwise they're just being dogmatic.
However, notice something about your immaterial mind. It, based on being simple (indivisible), being immaterial AND being uncaused is exactly identical to nothing. So, now I present you an analogical argument: — TheMadFool
I have twice now explained why this is obviously not so.
First, it is a conceptual truth that 'nothing' is not a thing. By contrast my mind is a thing.
Here's an argument for that (if one were needed):
1. If there are mental states, there is an object - a thing, called 'a mind' - that they are the states of
2. There are mental states
3. Therefore there is an object - a thing, called 'a mind' - that they are the states of.
And minds think, whereas 'nothing' does not.
That's no. 3. Three times now I have explained why minds are not 'nothing'. 3 times!
You're clearly just dogmatically assuming that if something is not material, it does not exist.
The evidence is that this is not so. The thing you're thinking with - the thing your reason tells you both exists and is indivisible, and thus simple and immaterial - is 'not material' yet 'is' existent