But it's not a valid logical argument because you have not concluded P1./C. You've just asserted all As are only Bs. It's a tautology. You haven't shown how all As are only Bs at all. You've just said its so.

An observation, rather.

My problem here is that either the argument is invalid, or the terms are being re-defined so as to have the implications you want. In either case, nothing is really demonstrated.

I don't mean to be rude but I'm not sure you understand how logic works. Maybe have a bit of a look over at the Stanford Encyclopedia of Philosophy?

Why do 'think' and 'perspective' drop out though?

Well, you replaced "think" with "mental." But perspectival != mental, unless you're redefining those two terms, in which case, whichever one is redefined drops out, and you're left with nothing.

Hope I'm not coming across as rude.

Not rude at all :)

I'm still not getting your point though. You think that I'm claiming that perspectival = mental?

Well, yes. You said that "All and only things you think are from your perspective." Then you offered to replace "think" with "mental." This would then be equivalent to "All and only mental things are perspectival," which is to say that "perspectival" and "mental" mean the same thing.

I know you don't know how it works, invizzy. How about that for some "rudeness?"

I've seen you do this all the time. You play convoluted words games and misread the use of those words for support of some concept you are arguing.

The argument you are trying to make would go something more like this:

P1. Property C is always found on As.
P2. Only Bs have property C.
P3. Anything with property C is an A.
P4. All Bs have property C.
C. All As are Bs
C. Any B is an A.

(or in long form: C. All As, and only As are Bs).

Your argument doesn't reason it conclusion. It doesn't have premise which lead to conclusions based on premises. You just say: "All As, and only As are Bs" and that's it. There is nothing showing why it is so.

Oh right, I think I'm with you. Yeah I think I am claiming that everything from a perspective is mental. That's what you would have to deny if you were going to argue against the conclusion. But I think it pretty obviously true that everything from a perspective is mental.

Under what definitions, though? There are definitions of the word "mental" that basically mean "thought," so that one isn't going to work. Perhaps you mean "having to do with the mind?" That's a more common definition, but then I have to ask you what makes a mind different from a perspective. If the answer is "nothing," then we're back to square one, because you've made made minds identical to perspectives. If the answer is anything besides "nothing," then there's a difference between minds and perspectives, and the argument falls apart again.

But you said it yourself, "Given P1., there is no possibility of a B which is not an A", therefore a completely valid conclusion from a premise P1. That is a logical argument in anyone's language.

No, that's an axiom or tautology.

If we accept that P1 is true, which we are in the context of the meaning of your argument, then there is no possibility of a B which is not an A. (hence you don't need C. or P2. to assert the point).

You haven't shown or concluded this must be so though. It's just the axiom tautology you've provided. You haven't given P1. any reasoned support.

What you are thinking of as a "logical argument" is not a valid argument but rather understanding of a basic definition. You are treating understand definitions as if they were a matter of giving a valid argument. Instead of realising we know what a definition means in the first instance (e.g. that saying "only As are Bs" means "there are no Bs which are not an A" ), you are working under the mistaken assumption that we somehow have to work thorough what a definition means, that we somehow have to exclude possible meaning it could have though reasoning about it with a valid argument. This is never the case. Any definition only ever has one possible meaning.

How about

P1. All and only (phenomenologicall experiences) are (from your perspective)

C. All (from your perspective) are (phenomenological experiences)

Does that suffer the same problems? It means everything is a phenomenonological experience, be it thought or sensation etc. I still think that is a form of Idealism.

Yes that's true. From my perspective. — invizzy

Why did you have to qualify with "from my perspective"? It suggests that things can be true from another perspective or from no perspective at all. But if a thing can be true from no perspective at all then idealism fails and if a thing can be true from another perspective then things can exist which I don't think of.

How about

P1. All and only (phenomenologicall experiences) are (from your perspective)

C. All (from your perspective) are (phenomenological experiences)

Does that suffer the same problems? It means everything is a phenomenonological experience, be it thought or sensation etc. I still think that is a form of Idealism.

The bit in bold doesn't follow. What (might) follow(s) is "everything from one's perspective is a phenomenological experience". The bracketed part of C. isn't optional.

Furthermore, if you can derive a conclusion from a single premise then that premise begs the question. Syllogisms require two or more premises.

And it is not self-defeating. We still have absolute truth, there IS absolute truth from your perspective. We can still be objectively wrong for instance. — invizzy

That is not absolute truth. By definition, absolute truth is absolute, and therefore cannot be relative to a perspective. You cannot be objectively wrong either, since the very meaning of "objective" entails that it is independent of (not relative to) any subject or perspective.

My refutation stands.

P1. All and only (phenomenologicall experiences) are (from your perspective)

C. All (from your perspective) are (phenomenological experiences)

Does that suffer the same problems? It means everything is a phenomenonological experience, be it thought or sensation etc. I still think that is a form of Idealism.

The bit in bold doesn't follow. What (might) follow(s) is "everything from one's perspective is a phenomenological experience". The bracketed part of C. isn't optional. — Michael

I agree, especially with that last sentence. That was what I was trying to show in a previous comment. Basically, what it seems invizzy is doing with the brackets fails, because the following two statements aren't equivalent, either in meaning or in terms of truth:

1. All (from your perspective) is phenomenological experiences. [Presumably true]

2. All is phenomenological experiences. [False]