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 notup 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.”
That sentence – called “Moore’s problem,” after its creator G.E. Moore – is interesting because it is a case of something which can be true and yet is impossible to believe. It’s perfectly possible for it to be raining and for me not to believe that it is raining. In fact, it’s happened many times. Yet, I can never believe it as it is happening.
Moore’s problem is not a very serious one. Fully accounting for it is a tricky logical exercise, but it is obvious that there is no real problem. You can’t both believe that it’s raining and believe that you don’t believe that it’s raining. Beliefs just don’t work that way.
Moore’s problem points to a broader issue, however: philosophical positions that can be true but cannot be believed.
Consider Freudianism: the belief that it is our primal, unconscious desires that govern our rationality. If this is, in fact, true, then whatever reasoning we used in order to reach the conclusion of Freudianism must have been an expression of our primal, unconscious desires. This means we have no reason to trust that reasoning in the first place. Our belief in Freudianism undercuts itself.
Or Marxism: the belief that class superstructures govern our rationality. If this is true, then whatever reasoning we use to come to Marxism is an expression of whatever class superstructures we are governed by. We have no reason to think that reasoning reliable. As with Freudianism, belief in Marxism becomes self-defeating.…