@Bonaventurian,
I suggest you read what I posted on page one.
The only situations which cannot occur are the logically impossible ones, those are incomprehensible. You are a set of facts in logical space. What you experience, what occurs, what
can occur is predetermined by logical possibility. You can move and feel and think and will but these cannot be separated from the facts, what is is not necessarily so because of any will. Now, that you will your arm to move can be refuted. The arm moves when you will, but to connect these facts all we have is correlation. Your will is not , and cannot, be shown to have a direct connection with what is.
So, can you decide? Or is it simply an illusion.(this is rhetorical of course)
It is not true that you cannot doubt that you are, you can; but it is without a logical direction that you do so. You would in a sense, doubt that you doubt if you were to doubt that you are. This is absurd.
That you are aware that the will has no connection with other logical facts is only a part of the picture. These facts cannot be shown to have bearing on each other, only that there is a pattern to their organization. We can speak of how our picture of reality is organized, but not of why it is organized or even how it comes to be organized. We can speak of a pattern of organization, this is science. We can speak of how things are and how they have been, and we can hope for the pattern to continue, but we cannot say that it will with any honesty.
So, is will attached to thought? Is it attached to anything but itself? I would say that we cannot know. We know that when we will a thought, it is conjured up(unless we are having a flashback or hallucination or compulsive thought ect.) but this is still empirical. So, we will a thought, the thought comes, the doubt is resolved, but are these events connected as directly as we think? I would say not necessarily, but that we also cannot know, for if there is a connection, it does not make itself apparent to us.
To keep a bit on topic: We 'know' that an animal can feel pain, at least more complex animals. They can become neurotic, they can fear(at least as their behavior indicates, which is as much as we can say for humans). To say that you do not want animal rights is to say that you would allow a creature pain that is unnecessary. I think that it is certainly worthwhile to afford livestock some room to move around and disallow brutalizing an animal. You may disagree.