Every waking moment, we are surrounded by a multitude of options. Get up and walk around, keep working, shift in our seat, text our friends, let our minds wander — the menu of possible next moves is thicker than an over-ambitious family diner's. Alongside this freedom of action is also a very strong sense of freedom of selection, or as it's most commonly known, "free will". Every time we talk to a friend, ignore an email, or even just lift our arm, we experience the sensation of having made a choice. It really feels like we ignored that email, but also like we could have just as easily earnestly responded. It feels like it so much, in fact, that we almost never try to look behind the curtain.
In looking behind that curtain, I find the concept of a conscious agent exercising genuine free will to be completely incoherent. In this blog post, I will attempt a bite-sized exploration of free will and why human beings very likely don't have it. In short: we might be able to follow our whims, but we cannot architect our whims.
The simplest thought experiment I know of that begins highlighting our lack of free will is recognition that every individual human being's personality, strengths, weaknesses, and anything else that identifies them, are defined by some mixture of their nature and their nurture. (Hang tight, believers in souls — your time is coming!) Consensus on the nature-vs-nurture ratio is not even remotely in sight, but most secular people agree that those two alone come together in concert to define each of us.
Continuing with this thought experiment — it follows that to believe in free will we must square with the apparent truth that we choose neither our nature or our nurture. The thought of choosing our nature — our DNA — is silly enough to spend scant time on, but many people feel intrinsically that they do exercise some degree of agency over their environment. We feel the effects of that exercised agency in our bones, every minute of every day, despite the fact that no one elects their parents, the time or location into which they're born, the quality of that setting's educational system, whether their government is at war or peace, or any of its other defining characteristics. These critical variables of our environment that define so much of life are simply handed to us.
"But what about my friends?" you might find yourself asking. "My friends greatly influence the arc and quality of my life, and I definitely chose them."
But, did you really choose your friends? Personally, I don't remember controlling the quality of my schoolmates, which ones I was shuffled into classes with, or, often, even which ones I shared group projects with and thus had a chance to bond with. The nature and distribution of like-minded people in my class and neighborhood were shaped by factors entirely outside of my sphere of influence, and I bet yours were, too.
"But my graduating class had hundreds of students," you might now find yourself asserting. "There was enough variety that I was able to choose the specific friends of my liking." Here, I want to knife in on the word "choose", because that is where the concept of free will drops off into total incoherence.
To choose one option over its alternates is merely to place higher value on its projected outcomes, and then act.
This definition seems almost too simple, but I believe it robust, even in the face of arbitrary counterexamples. You may be thinking of some counterexamples right now; you may be recalling instances where friends or family acted in ways they obviously could not have placed higher value, perhaps as part of an ongoing tendency toward self-destruction. How, one might ask, could a person truly value self-destruction over any of its alternatives? Granted, self-destructive behavior does seem alien to most of us, but I bet that in all such instances you successfully imagined an explanation. Maybe a self-mutilator is crying out for attention, or your ornery aunt is simply too petty to get along the family. The self-mutilator values human attention but lacks the confidence to secure it otherwise, while the petty aunt gets a rush of endorphins from cutting down those she "loves". Imagining self-destructive behaviors without any such underlying values should quickly highlight that any choice, no matter how superficially counterproductive, must be rooted in values. 
Of course, all of this doesn't actually imply much, but instead passes the buck to a new word — value. Given my proposal that our actions are inexorably bound to our values , to believe in freedom of choice is necessarily to believe in freedom of values. (Or, maybe more helpfully, freedom of value selection.)
This new phrase, "freedom of value selection", which I assert is logically equivalent to free will, has taken the first steps toward sounding like a different concept altogether. As I stated above — barring something like a physical disability, incarceration, or a gun to our heads , most of us are able to follow our whims. Choosing what those whims are, is, at a minimum, a circular sentence.
"But I have a soul," you might now find yourself saying, if you're a religious and/or spiritual person. (And even if you're not, let's run with this idea and assume that we do have a soul.) "My soul is the source of my true individuality and free will," you might say.
My understanding of the conventional Christian storyline for a new life is that at the moment of conception (or very shortly thereafter), a soul is assigned from heaven (or where ever souls hang out in waiting) to our new, microscopic, one-cell human being. Even if we grant this at face value, one thing seems extremely clear — the human being in question is simply given a soul and has no say in the matter. Each of us could either strike soul gold and wake up as a brilliant, loving philanthropist, or draw the short straw and wake up a cold, sociopathic killer. If various religions expand the formula for human individuality to nature, nurture, and a unique soul, they would seem to only have included a third ingredient just as outside of our control as the original two.
"But my soul has free will", you might now be saying. "My soul is unique and makes me the individual I am, and its values are what materialize as my free will."
If you were thinking that, brace yourself for just the first lap around the Pool of Infinite Regress. Since souls certainly seem to all be different (as evidenced by how different are the individual human beings they pilot), they must have gotten their attributes from somewhere. I ask, from where did your soul get it's values? Was it consulted when the values were selected? If it was consulted about what to value, how would it have chosen its answer? (Note that we just encountered a form of the word "choose" while trying to explore what it means to choose something. This is the root of the problem with free will.)
In various flavors of video games, a human player's first action is to specify what makes their character unique. If the setting is fantasy, the player might choose between a warrior, thief, or wizard. If the setting is contemporary or science-fiction, the player might choose between a soldier, pilot, or scientist.  The more advanced the game, the more specificity a player has over their character's unique attributes. Thus, you might also find yourself allocating resources to the character's physical and cognitive details, their various learned talents, or other qualities. For most first-time players of such games, the character they create is little more than an idealized version of themselves. These choices make sense, as idealized versions of ourselves are naturally the character attributes we value.
Any picture of soul-driven free will I have been able to momentarily hold in my head mirrors a stylized version of what I've described above. I imagine souls, fresh out of the Heavenly Repository, newly assigned to their human, exercising their free will in front of a hypothetical screen, selecting strengths and weaknesses from various options. Maybe one soul favors a hard-working rationalist and goes on to pilot the body of a molecular biologist that cures a disease, and maybe another favors a somewhat whiny but impressively upstanding super-athlete and goes on to pilot LeBron James. Either way, the soul's few minutes in front of the cosmic video game character creation screen are not fundamentally different from our own when starting a modern role-playing game. Such a soul is presented with various options and asked to choose between them, and to do so it must consult its values. Naturally, this means it cannot also choose its values, because then, what would it consult?
The following is a thought experiment I can't entertain for too long, lest I get a headache. But, to drive home the above points, I invite any yet-unconvinced readers to try to imagine choosing new values. If you value hard work and honesty, instead, try to imagine valuing theft and deceit. Focus on valuing that theft even if it comes at the expense of those you most treasure. If you value rationality and science, instead, try to imagine valuing anecdote and conspiracy. And, lastly, if you value strict adherence to religious doctrine, instead, imagine valuing the evolutionary fossil record.
If you're much like me, it's frustrating to dwell on the above sentences. That's because we are our values and we can't easily change them on our own accord.
(For additional fun, imagine living the rest of your life with drastically higher or lower value placed on updating your values.)
Changing one's mind can easily be confused with free will, but that mistake does not survive the microscope. A lack of free will does not imply that human intellect is a bronze statue, shaped by some initial process but then forever more immutable. A lack of free will only implies that, similar to our moment-to-moment whims, we cannot architect how ideas strike us. Not once in my lifetime have I had the experience of deciding how much sense something made to me. When I hear new information, theories, or explanations, they either make sense to me or they don't. Not once have I felt like my vote was counted. Similarly, when I hear a new idea and at first reject it, then later hear it presented again and adopt it upon this second encounter, I am no more in control than before. Maybe the idea was presented more coherently the second time, or maybe intermediate experiences have provided me with knowledge that filled in gaps I could not originally overlook, but in any case, I am but a curious onlooker to my own reaction.
If choosing something is merely a (often subconscious) reference to our innate values, and thus choosing our values is impossible, where do we get our values? We don't seem to be able to have gotten them from ourselves, theoretical souls, or even any imaginable deity (because, again, such a deity's values must have come from somewhere else). Something plain and simple and deterministic is required to terminate this regress. Something that makes no decisions, exercises no opinions, and just is.
Conveniently, just such a thing is found within every living organism on earth — our DNA. Human DNA completely dictates our preferences and initial dispositions, which are in turn radically shaped by the constant and evolving pressures of our environments. Jonathan Haidt defines the word "innate" in The Righteous Mind as "organized in advance of experience." New ideas and experiences constantly flood our minds, but the nature in which they are recorded and recalled as memories is dictated by our individual DNA. Ironically, DNA, the molecule of life, is actually cold and lifeless in any sort of free will sense. It makes no conscious decisions, exercises no opinions, and just is. DNA molecules do whatever the unflinching laws of physics tell them to do. This makes DNA the perfect terminator for our infinite regress problem. 
Luckily, I think human beings can recognize that they have no free will, that the very thought is an infinite regress, and then return to every day life with full enthusiasm for the illusion. I believe everything I've written here down to my bones, but none of it infects my minute-by-minute dealings. When hunger strikes me at 11:30 instead of noon, I simply enjoy the freedom to elect to take an early lunch break. When I'm at the grocery store and buy garbanzo beans instead of pre-made hummus, then go home and make it to my exact taste, I feel good and congratulate myself on making the even-healthier "choice". None of these moments are degraded by an inner siren screaming "Stop enjoying this, you dummy! You were always going to buy the garbanzo beans!"
I would never deny the power of our sense of free will. I enjoy a visceral sense of agency every waking moment. It feels as though at any second I could spring into a spontaneous, original dance just to prove the anti-free willers wrong.  This sensation of agency is undoubtedly a good thing, as life would presumably be less fun if our experienced relationship with ourselves was more analogous to our experienced relationship with the main character in a movie, where the plot simply unfolds before us and we never imagine an ability to influence its flow.
The importance of individual life goals is also preserved. As we specified above, changing one's mind poses no threat to a restricted-will worldview. This means that spreading good ideas can still meaningfully change the world by inducing better behavior from your neighbors. You can still actually reduce worldwide suffering by taking appropriate actions and convincing your friends to join you, and that actually matters. This means that with or without free will, we can all still accomplish real things and change the course of history by spreading good ideas.
I wake up every day both hungry to take on the world and thankful that I have that hunger. You can too, even without glossing over the infinite regress involved in assigning conscious agency to your actions. You can even still feel #blessed and special all day long, and in fact you are, because out of all the astronomical number of atoms in the universe you could have been, you're you, a conscious human being capable of experiencing agency. And while you might not actually have that agency any more than a comet tumbling through space, you're right to prefer not trading places with it, and that's pretty neat.
I can think of two reasons, both of critical, societal importance. The first is that (to my knowledge) all modern religions square the "Problem of Evil" with various handwaving about human free will, thus blaming our world's abundant suffering on human beings instead of their all-loving god. To explore the rocky, self-contradictory terrain of free will is to naturally cast scrutiny on modern religions that depend on it so heavily. The second reason is that so many pillars of contemporary morality stand on a notion that people get what they deserve because of various choices they've made. However, if human beings have little more control over their values than they have over the weather, current patterns of incarceration may need immediate review. For my money, locking up violent offenders remains perfectly defensible, as we are still right to value a non-violent society, but slamming the bars closed with hate and anger in our hearts helps nothing. Similarly, incarcerating non-violent drug addicts becomes one of the all-time sins a society can commit against its own citizens. It is such rickety moral footing we stand on when compounding the poor luck of an individual born with compulsive, addictive behavior by adding on life-ruining jail sentences. 
In short, I don't think the illusion of free will, embraced on a daily basis, by itself causes any real harm. I don't mean to reduce the minutia of daily life, often enjoyable as it is, to a nihilistic husk, but I do mean to undermine the misguided beliefs propped up by a worldview built upon the notion of free will. We are who we are, and no amount of tinkering with the system can change that. However, you can still internalize this idea, square with its implications, focus your energy on your own personal strengths, and then figure out how to channel them in ways that make the world a better place for everyone.
And really, free will or not, should we be doing anything else?
: This is true even of knowingly choosing a worse option as a practical joke or troll. Indeed, such a person simply values the prank more than they value a straightforward interaction. In this light, it is by definition impossible to do something on which you place lower value than one of its viable alternates. Even if you read this paragraph and, in frustration, commit a badly self-destructive act just to prove me wrong, you'll have only demonstrated that you place extremely high value on any attempt to prove this concept wrong. This is not a deep insight or an observation — it is a tautology.
: Our actions are inexorably bound to our values through the filter of what is physically possible. The laws of physics prevent most of our wildest fantasies from spontaneously coming true, but this does not change the hard relationship between values and choices.
: The gun-to-head scenario may seem like an affront to free will, but it is not. Imagine a scenario where, with the ransomer's gun to your temple, you calmly instruct the bank to wire all your money into a Swiss bank account. Did you exercise free will there? Of course not! You (wisely) valued escaping a situation without being shot in the head.
: Do video games let players control scientists? If not, they really aught to.
: The nature by which DNA drives us to all varieties of seemingly conscious decisions is by unwinding and copying itself into its mirror molecule, RNA, which builds the proteins that constitute us. Some of those proteins are neurotransmitters in our brains, the balance of which decide every nuance of our pre-nurture character. If you doubt this, consider for a moment how Prozac works to radically alter the personality of many people suffering from chronic depression.
: Though, curiously, I have only ever had the desire to spontaneously spring into such a dance whilst dwelling on the idea of genuine free will.