Here's an interesting article on neuroscience trying to prove that human beings do not have free will. These researchers asked people to choose between clicking a button with their left forefinger and clicking another button with their right forefinger. Test subjects shown a rapid, random sequence of letters, with the choice of whether to click up to them. They were asked to note when and what letter was showing when they clicked, that is, when they were aware of having made a choice. They were also placed in an MRI to monitor brain activity during the process.
Results show, they claim, that the decision was predictably preceded by a particular pattern of brain activity, in some cases as much as seven full seconds ahead of the choice. Based on the brain activity, researchers could predict the subsequent choice with 60% accuracy--better than chance, but not very accurate.
Now, this particular article leaves me asking some questions. For instance, what exactly is the working definition of being aware of having made a choice? Is it the moment of actually pressing a button? Can't someone make a choice before externalizing it?
Also, the researchers seem to believe that the choice is between two alternatives, clicking the right or left buttons. But I see a total of at least 5 options at work, maybe more. The two the researchers proposed, plus the option to not click either button, and to hold off clicking the right, and to hold off clicking the left.
I personally believe the choice is far more complex even than 5. What about the "next-I'll-choose-left-but-wait-awhile-and-then-CLICK-oh-I-meant-to-click-my-other-left" choice? Or the "change-my-mind-in-the-middle-of-deciding" choice? I could imagine myself as a test subject thinking, "OK, next I'll click the right button.... Now!--NO WAIT--OK, NOW!... alright next let's see... I'll click left NOW, ok, that's done.... what shall I click next? I know, I'll click the left button every time I see an M, and the right one when I see an A.... now I'll play air guitar for a while and be sort of random...." I suppose some people might be more straightforward, but even the straightforward and diligent persons will be thinking about what they're doing.
But at any rate, the choice to click would likely be made well ahead of actually clicking. In many cases, the act of clicking may not even be a real choice, but a kind of reflex response to the pre-made choice, so the test may not be testing free will at all. Free will isn't really about choosing which unimportant button to click. Because the choice doesn't really matter, neither does it matter if it's free or reflex.
St. Thomas Aquinas locates free will in the deliberation in selecting a means to a particular end, since we are always inclined to some good in the end we seek. Also, all ends are means to further ends, except the Final End, which ought to be God. Therefore, a proximate end, insofar as it is also a means to a more remote end, is also an object of deliberation.
Because all ends are also means, they become ethical or moral by virtue of the more remote ends to which they are ordered, and of course whether or not they are ordered to a suitable final end. If "I" am my own final end (or riches or fame or power or pleasure, which conduce to "me" being the final end anyway), that would cast a shadow over the morality of all of my choices.
At any rate, free will is in the choice of a means. "When" to click a button is only part of the deliberation. "Which" and "whether" and "if so, under what circumstances" are also part of the reasoning process going into the actual decision to click.
This neuroscience study does not seem properly designed to test all that. And even if it were, it would only show brain function, not freedom or lack thereof. That brain function could still be an instrumental rather than pure efficient cause, and thus evidence of the intellectual soul using the brain to deliberate ahead of the act of clicking a button.