I have an argument against free will called The Two-lever Argument. There are many definitions of free will, so we should start with one before proceeding:

free will The ability to have willfully chosen otherwise for any previous decision.

The Two-lever Argument says that there are only two ways to influence future events (and thus have free will): 1) by controlling a previous state of the universe, or 2) by controlling how that state transitions to the next.

To illustrate this stepping through time instant by instant, here are 25 lines of code that start one instant after the big bang and then check the two requirements for free will for each one:

Here’s what it looks like when executed:

All the universe’s instants seem to work this way, including the one that just passed…and the one about to come…

It may seem overly simplistic to model the levers of choice in such a way, but that is precisely the point. The burden is on the the believer in free will to provide the variable to add to this code to grant humans authorship in the process.

I’m not saying that code doesn’t exist. What I’m saying is that there is no evidence that it does, and that if someone wants to model it then let’s see it in the code.

The most common answer to that is simply:

Well, we don’t know what the mechanism for free will is yet, so we can’t add it to the code yet. All I know is that we have free will, so it must be in the part of physics that we don’t yet understand.

This is the God of the Gaps argument. Anything people want to be true, or already believe is true, gets stuffed into the part of the universe that science doesn’t yet understand. That’s no longer an option available to the intelligent and educated.

When confronted with a mechanistic universe where outcomes are functions of previous states of the universe, we have no intelligible lever even imaginable to science that would grant us authorship, and it is ridiculously unscientific to grasp into the void of ignorance and call that a solution.

In short, I’m not saying this shows that free will cannot exist. I’m saying that this demonstrates quite clearly that there’s no reason for us to believe that it does.

To debate the argument rather than the code, please refer to the argument itself.

Notes