Assume you have been charged with a crime. In court you are able to conclusively prove that free will does not exist and therefore you can not be held responsible for this act.
Although this seems more to be a legal than a philosophical problem, some core issues of philosophy are embedded in this scenario.
From a pragmatic point of view, if I was the judge in this case I would simply argue that I am forced to sentence you for the crime, as also I have no free will in this matter.
The idea that it would be scientifically provable (the only type of evidence that would be acceptable in court) comes from the reasoning that since we are made of material components and that since those components follow the ‘laws of physics’, our behaviour is a result of predictable interactions between atoms.
This idea is contrasted with the view that, although we have physical bodies, we also have something non physical, which does not follow the laws of physics, allowing for free will.
I don’t want to delve into the discussion between the materialist and idealist points of view in this article, as this is a philosophical minefield. For the purpose of this thought experiment, we need to assume that it has been proven that our minds and therefore our behaviour follows causal relationships and is therefore, assuming we can know the starting conditions and have full access to the laws of physics, fully predictable. Free will does in this context not exist and what we perceive as free will is to be considered an illusion.
The philosophical question that this thought experiment poses is what would the world be like if there was overall agreement that we are biological without free will. The consequences for our culture, our societies and our psychologies could be devastating. The philosophical problem is thus an existential one.
Some would argue that being deprived of a free will removes all morality and meaning from life because without will there can be no humanity—all our triumphs and digressions can be simply be blamed on causality. The person in our imaginary court case would argue that it wasn’t him or her that perpetrated the crime, but the laws of physics.
My position in the materialist/idealist discussion is towards the materialist. Although, this does not mean that I think we would ever be able to conclusively prove that either is the case. Also, I think our so called ‘laws of physics’ are based on a logical error, as shown by David Hume, but that is food for thought for another time.
In the hypothetical situation of this thought experiment I think that society would not come to an end. In some ways it would be great for society because it would bring philosophical thinking to the foreground. Everybody would have to take position in this situation.
If humanity would be without free will, meaning and morality would most certainly not collapse. In some ways it would be very good for those who try to provide morality with a rational foundation—because if our minds are based on pure causality, than it would be possible to construct moral algorithms.
As for the question whether lie has meaning or not, I don’t think that having no free will makes any difference. But for that question I refer back to the tireless Sisyphus, rolling the boulder up the hill till eternity.