I was under the impression humans do not have free will. All evidence points to this. Sam Harris has a good speech on the topic. Basically, no matter how you put it it can't possibly be. You can have logical cause/effect thinking and decision making, which isn't free (this is what we have) or you can have completely random and arbitrary decision making, which isn't free. Either way, the decisions made are not free. Unless you mean the act of controlling our bodies is "free". But that still is hard to say. Our bodies and minds follow the laws of physics. Sure, they can do a variety of things, but you can't simply break physics just to make a decision. And even if you could, it'd be arbitrary. And that's without getting into the topics of what makes up the mind, the law of cause and effect, time and relativity, etc. Edit: I forgot to mention that I voiced my opinion and thoughts (although briefly). But I agree, people should comment rather than just share. But some people may not be able to comment right away but still want to see where the discussion goes.
I like the argument about cause and effect being an indicator of no free will. People make decisions based upon a variety of factors and every input of a new factor changes that decision to a certain degree, no matter how off the wall that factor may be. You can try to fuck with the end decision as much as you want but every new input is still a defining element of your decision. Imagine a scenario like the OP explained where the subject is thinking about purchasing a bike. Childhood memories are clearly a factor, as are ease of travel, thrill-riding, and exercise. Those inputs are all internal, within her mind. Externally, inputs might be that it's wonderful weather for a ride, bike sales are on, or her friends are into it. Regardless of of the quantity, variety, or type of inputs, they all determine her decision to some degree. Even if she has the ability of foreknowledge and can "know" her final decision, she is still determining her decision through another input. And even if she tries to change that decision, that change is inspired by the foreknowledge (cause) which is another input. It's impossible to act arbitrarily because - as said earlier - any attempt to fuck with "fate" or the established flow of time takes conscious thought: the impulse to act. Coming up with an original idea that might interrupt time flow - like swinging my hand for no reason - is still caused by a reason: the desire to screw with pre-established order.
I don't have time to watch what I assume is a video you linked. Maybe later. But free will is not, I think, freedom of choice. A child born in Mogadishu has the same free will that an American billionaire has -- but the gap in freedom of choice is apparent. I think that making the argument that because we are bound by gravity, or by the consequences of our actions, we don't have free will -- that's semantic silliness. I may not be giving your idea due diligence; if not, I apologize, feel free to correct me.
My main point is that "free will" is not clearly defined. Once you define what you mean by the question, then we can answer. However, the idea that there is some separate non-causal entity that is making decisions is ridiculous. Okay then. Yes, it's semantic silliness. But that's all we really have until a clear definition is provided. The question of "free will" is really only one by those who don't understand how brains work. We have clear evidence (and many experiments) of various sections of the brain and how they affect consciousness. It's very clearly tied. Our current and past experiences add up, and go through various biological "calculations" and then fire off the correct nerves and muscles in order to respond. None of that is really "free". The same thing would have happened every single time. Since that's what the body/brain calculated to be the "correct" response. The body could have calculated a different answer, had it been in a different state or if any other parameter was changed. But with the same parameters, and the same internal configuration, the brain arrived at it's conclusion. The video I linked to discusses this a bit further in detail (a lot better than I could probably explain). But it boils down to this: Your thoughts and actions are tied to your brain activity. Your brain activity is based on and modifies itself based on various experiences and perceptions. Each person has different perceptions and experiences, so we come up with different decisions. But if we trace it back far enough, we can clearly see where the thoughts came from. So if we were to "rewind" time, the decision would be the same, every single time. You could argue that due to the nature of quantum mechanics and stuff being "random" that we could theoretically pick something else. Our brains don't really work like that. But if they did, we'd simply randomly make decisions, rather than being based on internal logic and perceptions. Neither of those are really "free". One is pre-determined based on the state of the environment and person. The other is arbitrary and random. So when you come and say "we have free will", I'm wondering what the hell do you mean by "free will"? I know plenty of people subscribe to the body-mind duality hypothesis. But we've already proven that to mostly be false (physical things affect consciousness). But even if mind were separate from body, there's still no proof or evidence that "free will" is even there. And logically, the idea doesn't make sense. TL;DR: Free will isn't adequately defined. Once we come across a definition we can say whether it's true or not. But the seemingly most common definition is nonsensical.But free will is not, I think, freedom of choice.
I think that making the argument that because we are bound by gravity, or by the consequences of our actions, we don't have free will -- that's semantic silliness.
I'm always willing to entertain an argument that endeavors to answer social science with actual science, which is what my skim of your post is suggesting. I also agree that 'free will' is a strange phrase, which is why I'm not a fan of this debate like I am of so many others in philosophy. However, I have to go to work. But I'll leave this in my notifications and read it later. EDIT: unfortunately, I think we know a lot less about the brain than you seem to think. And I don't think you can predicate an entire argument against free will on 'the brain will always do the same thing in every situation'. I'll try to watch that video at some point, though.