How do you know that you are consciously making the decision and not just consciously acknowledging the pre-determined direction give to your body by your brain depending on the factors which are affecting it.

This is an interesting question, and one that has been discussed quite a bit by philosophers and by scientists, some of whom suggest that there is evidence for the sort of picture you describe--i.e., first the brain initiates a decision and only then do we become aware of having made a decision. I think it is possible that our non-conscious brain processes do all the interesting deliberative work and form decisions and then our conscious brain processes simply become aware of the final product and perhaps make up some stories (rationalizations) for why we made the decisions we did. But I don't think the evidence has shown that this account is actual.

First, we need to avoid a common mistake, which is to think that if our brain does it, we don't. It seems very likely that in some sense, we are our brains (our mental processes are very complicated neural processes), and we do not have non-physical minds that make decisions and then "send them" to the brain. Once we understand the mind in this naturalistic way, then when our brain does it, it is our minds doing it.

But even on this picture, it's possible that the conscious processes of our brains don't do much or do it too late in the way suggested above. And this may happen sometimes, perhaps more than we think (of course, it's a good thing it happens for many things, since being conscious of too much would be a bad thing!). At a minimum, however, I think it is very likely that when we have important or hard decisions to make and we deliberate carefully about the various alternatives for action (humans are likely unique in our ability to consciously visualize possible futures--e.g., "if I do this, that would happen, but if I do something else, then that would happen, etc."), and then we come up with decisions about what policies or plans we want to guide our future, then that conscious mental activity has crucial causal influences on what we end up doing (perhaps sometimes what we end up doing without then thinking much about it at the time of action).

If you've ever prepared a lecture or just thought about what you want to say to a friend in need or such, perhaps your experience is like this: you thought hard (and consciously) ahead of time about what to say and then you basically let yourself (your non-conscious brain?) go and ended up saying basically what you wanted to (consciously adjusting things along the way).

Some names you could google to see discussion of all this include scientists who raise the worry you ask about, such as Benjamin Libet, Daniel Wegner, John Dylan-Haynes, John Bargh, and Jonathan Haidt, and a philosopher, Alfred Mele, whose new book Effective Intentions responds to some of these scientists (as do I in some of the papers on my website).

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