Compatibilism vs. incompatibilism
If existentialism means anything, it means believing in freedom. Jean-Paul Sartre, probably the most well-known existentialist, argued that, in all situations, we are free to choose between options. In fact, though existentialism is a diverse and complex school of thought, it boils down to the following two claims:
- Radical freedom: we are always free to choose how to act.
- Radical responsibility: we are personally responsible for our entire experience of life.
This should sound utterly incompatible with determinism: the view that causality is an exclusively physical phenomenon. If all causality reduces to the interactions of physical matter and forces, what room is left for personal choice? This isn’t even a question about whether physical states of affairs fully determine how everything will turn out (“hard determinism”). Even if some level of probability or even randomness enters the picture, so long as it all happens in the realm of the physical, then, whichever way it happens to work, it’s still not up to us.
Or, to put it more precisely: even though some of it is up to us, how we choose to influence what is up to us is not up to us. We obviously do choose. But how we choose is only the manifestation of physical causation doing its thing. As Schopenhauer put it: “Man can do what he wills but he cannot will what he wills.”