Why not? Why should I believe I on my own cannot be a cause of one of my decisions?
Because stating that "the cause of X is
me" is different from saying "the cause of X is
a mental state of me." A ball rolling into another ball causes the second ball to move. The ball on its own causes nothing - it just sits there. The ball has to be combined with properties of hardness and movement for anything to happen.
Likewise
you on your own cause nothing, it is the mental states which make
you up that have causative power.
A mental state would be the cause if I acted irrationally perhaps, but normal decision making, that comes from have a normal mental state in which the brain is used and conscousness is obtained and decisions are the result---i.e. caused by my brain and consciousness and normal mental state.
What, other than your mental state, can be the cause of your decision? Remember your mental state is the sum total of everything in your mind at any one time - it includes thoughts, ideas, emotions, memories, immediate sense data and more.
I don't understand what infintie states have to do with this issue. While there is a sense in which I cannot control my mental state, there is also a sense in which I can control my actions regardless of my mental state.
Again you are ignoring my argument and essentially repeating what you've already said. The point of an argument is that, if you follow it, you are forced to the conclusion. You can't just deny the conclusion and leave it at that!
First, let me say that there is no way in which
you can control your actions if
your mental state does not
entirely control those actions. Your mental state - your thoughts, memories, etc,
must be the agent behind a decision if that decision is made by you - if something other than your mental state (your thoughts, memories, etc) causes the decision, how can it be you who made the decision?
Now, you say that you (and I will assume you agree that this must mean "one of your mental states") control your decision. So I ask, what controls that control?
Is it another mental state, or is it something outside you? The trichotomy is that, after I ask you this any number of times, your answer must be one of three things:
- It is another mental state
- Nothing caused this mental state
- Something outside me caused this mental state
You can't keep answer (1) - that is where infinite regress comes in. You've not existed forever, so you can't just have infinite mental states.
And you can't answer (3) because then that is admitting that your decision was actually caused by something outside you.
So then you are left with (2) which means you have something which
nothing caused. But such things don't exist, as far as we can tell (ignoring quantum mechanics, but as I say, if you want I can form a slightly different version of the same argument which gets around that) so (2) is not a viable option either.
So the only option that isn't absurd is (3). Now, to argue back, you either need to produce a fourth option, or defend (1) or (2).
Why should I believe that to be true? Why does something other than me have to be the cause of my decisions? Why can I not be the cause of my decisions?
... Those statements were a summary of the conclusion of the argument. Is there a point of the argument you wish me to clarify? The idea is that the conclusion (something other than you caused your decision) follows from the argument.