It seems to me that humans don’t assess cause and effect very well; we had to invent the scientific method as a way of teasing out which causes of a particular effect are the important ones. That’s a comforting illusion for us, but causality is not a chain of events and causes, it’s more like a lattice-work stretching backward in time to the Big Bang. In practical terms, it doesn’t make much sense for us to answer “Why did the chicken cross the road?” with “The Big Bang” even though it’s true: we search for something we can pin it on immediately.
We look around and see the coyote stalking the chicken and say “That’s why the chicken crossed the road!” while simplifying cause and effect down to a single sequence, in fact there were intertwined causal meshes that put the coyote there, intertwined causal meshes that put the chicken there, and intertwined causal meshes that put the road there for the coyote to chase the chicken across. Our world would be too complicated for us to cope with, so we simplify the more tenuous chains out of the picture. But if we think about it, we have to acknowledge that everything in the scenario is a necessary precondition for the scenario happening at all: there first had to be domestic chickens, or was it eggs?
When we simplify our view of cause and effect, we also create a side-effect that I call The Path-Forking Problem: it’s our tendency to look at a simplified view of a particular situation’s causes, then imagine that if we could change just one thing, the outcomes would otherwise be the same. I think it’s this simplification that’s at the root of time-travel stories: we imagine going back in time and changing a single cause, then let the clock run forward again and in all other respects everything works out the same way. But it won’t! When we go back to the fork in the path, and decide we’re going to take the other fork we assume we’ll toddle cheerfully down the other path, just like we did on this one, except – I don’t know – there won’t be a hungry mountain-lion on the other path like there is on this one. The path forking problem manifests itself in our thought, “If only I had taken the other path!” or “If I could go back in time and kill Hitler!”
Back in 1999 I had a chance to sell the company I had started, for a sizeable sum. The company that wanted to buy mine got bought by IBM for a very large sum, 3 months after I turned their offer down. So I would occasionally imagine that if I’d accepted the offer, I’d be exactly the same as I am now, except that my investment portfolio would have 6 or 7 more zeroes on the right-hand side of the total. But of course that’s an illusion: I might have taken the deal and been dead a year later, after wrapping a sports car around a tree. It’s not even possible to assign a likelihood to either of those paths, because there are infinities of things that never happened, that I can’t assign any likelihood to because I can’t imagine them all.
When I started to think about this, I realized that second-guessing your actions is an action, too – one which irrevocably changes the situation. That time it took for you to think, “I wonder if I should have taken the other path?” may be the time it takes for the mountain-lion to leap. Because all of the causes of an effect are necessary for it to have happened, the slightest change to any of them destroys the entire mesh of events that get us there. Stephen Jay Gould explains this in his book “Wonderful Life“: it appears that Pikaia Gracilens was a common ancestor of everything that has a spine; if something had even slightly altered the life-outcomes of some of them, the entire history of life on Earth would be unimaginably different. We don’t get to say “there might not be humans” and imagine that there still might be coyotes (or chickens) crossing roads. Or roads at all.
When this started to sink in for me I realized that every apparent decision – even the most insignificant – is irrevocable and utterly life-changing. One of my father’s friends was a heavy smoker and I told him “Mr Rose you should stop smoking” (I was about 14) and he told me that when he was on watch in Bastogne one night in December, 1944, he ducked his head to light a cigarette and a German bullet went by just where his head had been a fraction of a second before. But again the path-forking problem rears its head: perhaps if he hadn’t been a smoker, he wouldn’t have even ended up in that part of Europe at that time at all.* The infinity of possible futures expands out immediately from every point in the web of causes and effects and speculating about them is attempting to imagine an infinity of possibilities.
Then, I sort of felt like I understood what “living in the moment” means. We’re trapped like flies in amber in these webs of cause and effect. There is no “maybe” or “I wish” there’s only what is. What wasn’t doesn’t matter. What could have been isn’t even an illusion, it’s not meaningful enough to be an illusion: it’s a side-effect of our imagination, which is a mechanism we use to conjure possible futures so that we can convince ourselves that we choose between them.
Often, when we discuss “Free Will” there’s a dichotomy between determinism and “freedom” – the ability to decide which path we go down and the outcome of that decision. When I used to debate free will, I’d go back and forth on that balance, but now I understand that it’s uncontrollable incomprehensible randomness down one path, and random uncontrolled incomprehensibleness down the other; it just doesn’t matter. Free will compatibilists like Daniel Dennet make a big deal out of our “choice” while (Dennet, at least) accepting that the “choice” is largely illusory, its the future-predicting engine of our imagination running backwards and pretending it can understand and pick between possible pasts.
The chicken is free to imagine all the possible reasons it crossed the road, and the infinite options. I remember a comment by Richard Rosen on USENET back in the 80’s:
Anything is possible, but only a few things actually happen.
We’re machines that program themselves to think they can predict the future. Sometimes we even get it right. But usually that’s when the possible futures are fairly tightly controlled by physical law: if you jump out of an airplane, you are almost certainly going to go downward.**
(* He did die of lung cancer. But 40 years later than 1944.)
(**I always interpreted the surreal scene with the alien spacecraft in Monty Python’s “Life of Brian” as a particularly pythonesque commentary on our belief we can predict the likely effect of our actions)