What do we do while deciding if free will exists?

[Pyrrho]

I've been putting some thought, and actually doing some reading on the idea of free will.  It's existence is one thing.  I'm leaning towards it not being a thing, and probably consciousness being an illusion as well.  But it's mostly guesswork for now, which is all that's relevant.

The problem is the implications of that uncertainty. 

I think the first thing you need to do is precisely define "free will."  Before you attempt that, I recommend, at a minimum, reading the following encyclopedia articles:

https://en.wikipedia.org/wiki/Free_will

http://www.iep.utm.edu/freewill/

http://plato.stanford.edu/entries/freewill/

These discussions typically begin with someone assuming that the meaning is clear and that everyone agrees on it.  That is wrong, and it leads to much wasted time and verbiage.

How one would behave in a world where people are responsible for their actions, and one where they aren't are totally different.

There is no necessary difference between how one would act in a world where people are responsible for their actions and one in which they are not.  And you should explain, very clearly, how this relates to the question of whether people have "free will" or not, whatever that phrase means, which needs to be clearly defined for us to have a productive discussion.

In a world where they are, we're free to judge and despise them.  Feel superiority, etc.. And it's all fine, because we chose to be who we are, and they chose to be who they are.  

In it's absence, however, that's the equivalent of yelling at the weather.  We don't believe a tornado is a jerk.  Instead we'd focus on getting a desirable outcome.  Things would be dealt with in a very logical way, as we attempted to dissuade/modify behaviors to get them to fall in line with whatever it is we want.

You seem to be presuming two separate things with that.  First, that we know the truth, whatever it might be.  There is no reason to presume that.  If we have "free will," we may or may not know it, and if we don't have "free will," we may or may not know it.  Second, you are presuming that we would either freely choose to behave differently, or, perhaps,  that we would be "caused" to behave differently (if you suppose this second thing, you will want to explain "cause" to us).  You have not given us any reason to suppose that that would be the case.  If we have no responsibility for our actions, that does not necessitate us not judging or despising others or feeling superior to others.

Or perhaps judging/despising/feeling superiority is the answer that evolution came up with that is more effective at getting the desired results than becoming aware of free will being an illusion, and acting accordingly based on that understanding?

Key point:  
When you have a concept that defines how you should live, and you don't know the true nature of that concept, how do you go forward?  Does it matter to people that their belief/non-belief in free will has a decent chance of being a fallacy upon which so much of their live's decisions are built? 

I have never known anyone to behave substantially differently, based on whether the person claims to believe in "free will" or not.  The wise ones look both ways before crossing a street, and the fools do not.  Claiming a belief in "free will" or not is irrelevant.

As for how to treat criminals, the practically-minded people focus on rehabilitation for those who will eventually be released from prison, regardless of whether they believe in "free will" or not.  But those who are angry and want vengeance often do not consider the practical import of how criminals are treated.

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I'm very surprised people act like this isn't a practical issue, when we've already seen it applied repeatedly in society.  I've always felt the idea that being gay was genetic rather than a choice was what put them over the top in terms of gaining a consensus of support. ...

I disagree.  If it is genetic, then one might want to use medication to cure the genetic disorder (if, that is, one views homosexuality as a disorder).

In my case, whether my neighbor is gay or not has no significance to my life, so I do not concern myself with the question.  It seems to me that the issue is a question of whether one wants to control other people's behavior or not, in cases where their behavior is irrelevant to one's life.  Whether other people are caused to be gay, or choose to be gay, seems to me to be quite irrelevant to the matter.

In the same way, I do not care if my immediate neighbor is black or white (or something else), though I am pretty sure that that is not merely a matter of the individual choosing.  And in the same way, I do not care if my immediate neighbor is a stamp collector or not, though I am pretty sure that that is a matter of the individual choosing (in the ordinary dictionary sense of the word "choosing," not necessarily in the sense in which you are likely to use it in this thread).  Neither the color of my neighbor's skin, nor whether he or she is a stamp collector, is of any importance to me, and so I take no action regarding these matters.

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I'll add one more thing.  This is from the Wikipedia article about David Hume:

Free will, determinism, and responsibility[edit]

Hume, along with Thomas Hobbes, is cited as a classical compatibilist about the notions of freedom and determinism.[87] The thesis of compatibilism seeks to reconcile human freedom with the mechanist belief that human beings are part of a deterministic universe, whose happenings are governed by physical laws. Hume, to this end, was influenced greatly by the scientific revolution and by in particular Sir Isaac Newton.[88] Hume argued that the dispute about the compatibility of freedom and determinism has been continued over two thousand years by ambiguous terminology. He wrote: "From this circumstance alone, that a controversy has been long kept on foot ... we may presume that there is some ambiguity in the expression", and that different disputants use different meanings for the same terms.[89][90]


Hume defines the concept of necessity as "the uniformity, observable in the operations of nature; where similar objects are constantly conjoined together",[91] and liberty as "a power of acting or not acting, according to the determinations of the will".[92] He then argues that, according to these definitions, not only are the two compatible, but liberty requires necessity. For if our actions were not necessitated in the above sense, they would "have so little in connexion with motives, inclinations and circumstances, that one does not follow with a certain degree of uniformity from the other". But if our actions are not thus connected to the will, then our actions can never be free: they would be matters of "chance; which is universally allowed to have no existence".[93] Australian philosopher John Passmore writes that confusion has arisen because "necessity" has been taken to mean "necessary connexion". Once this has been abandoned, Hume argues that "liberty and necessity will be found not to be in conflict one with another".[90]


Moreover, Hume goes on to argue that in order to be held morally responsible, it is required that our behaviour be caused or necessitated, for, as he wrote:

Actions are, by their very nature, temporary and perishing; and where they proceed not from some cause in the character and disposition of the person who performed them, they can neither redound to his honour, if good; nor infamy, if evil.[94]

https://en.wikipedia.org/wiki/David_Hume...onsibility