When I read Eleizer's posts on free will, and then spent time thinking it through myself, I came to the conclusion that the question was (non-obviously) incoherent, and that this is what Eleizer also thinks. More specifically, that when you Taboo free will you find yourself trying to say that your brain is not controlled by physics, rather "you" do, where "you" has to be not physics, which is really just "magic". I started thinking further about questions and realised that there are whole classes of questions for which neither "Yes" or "No" is the correct response. The most basic example is a contradiction. P = A is true & A is false.
"What would it feel if we actually had P?" "Uhh, hold on a second, that is nonsense." "I know we can't have P but what if we did! What would it feel like??"
I find this understanding incredibly valuable, because it is a traditional philosopher's downfall that they try to answer every question no matter what. You can fully explain the problem with the question yet still feel like there is a question. So the problem becomes psychological instead of philosophical and can be attacked by figuring out what our brain is doing when it tries to tackle the question.
Additionally, I think it is a Mind Projection Fallacy to ask a question like "What would infrared look/feel like if we could see it?" Stimuli don't necessitate particular perceptions. You could rewire your blue and red photoreceptors in order to feel blue, I mean, 420nm light, as red [untested]. I'm mildly confident that this can be extended to asking about how free/not free will would feel like. It's likely you can run with certain aspects of the idea without going loopy I still think the overall idea is wobbygobby.
Another mistake is thinking that being unpredictable gives you more free will. Either you are controlled by predictable atoms or controlled by unpredictable dice rolling mechanics, or what ever. Neither case gets you any closer to having "you" in charge. I even prefer being predictable rather than randomised. That shit's crazy.
Anyway, I expect I'm going to get a lot of disagreements stemming from us having different ideas about free will. Everyone struggles to formalise from the informal in different ways, so if you see something I've said as nonsense, ask yourself if it is just that we are using the same string of characters to point to different ideas.
I find this understanding incredibly valuable, because it is a traditional philosopher's downfall that they try to answer every question no matter what.
Just a nitpick, but this is true of no philosopher, living or dead (by which I mean I can give you examples of every significant philosopher rejecting a question at some point). The idea that we should always keep the 'reject the question' door open is good advice, but we shouldn't frame it with some historically false claim.
Given the spike in free-will debates on LW recently (blame Scott Aaronson), and the usual potentially answerable meta-question "Why do we think we have free will?", I am intrigued by a sub-question, "what would it feel like to have/not have free will?". The positive version of this question is not very interesting, almost everyone feels they have free will most all the time. The negative version is more interesting and I expect the answers to be more diverse. Here are a few off the top of my head, not necessarily mutually exclusive:
Epistemic:
Psychological:
Physical:
For me personally some of these are close to the feeling of "no free will" than others, but I am not sure if any single one crosses the boundary.
I am sure that there are different takes on the answers and on how to categorize them. I think it would be useful to collect some perspectives and maybe have a poll or several after.