Maurice Merleau Ponty argues that experience is shot through with pre-existent
meanings, largely derived from language and experienced in perception.
He denied that there is a causal relationship between the physical and the mental, and he therefore finds the behaviourist account of perception, entirely in terms of causation, unacceptable. Gestalt theory he finds not false but not developed sufficiently to do justice to the facts of perception. His general conclusion is that a new approach is needed if perception is to be properly understood.
There’s definitely an element of Stoicism in existentialism, particularly in Sartre, and also in Viktor Frankl’s work. The difference is that there is more emphasis on the need for human beings to find a meaning and an individual purpose in what they do. It’s not just a matter of enduring or retreating into an inner realm in which you’re free. In fact, it’s not really about the inner realm at all, because the way you find meaning is not within, but through a purpose in the world, something that’s outside you, something that is greater than you. It could be by creating something, and it could be — and very often is — connections to other human beings, whether it’s comrades, friends, family or the people you come up against in life. And if all else fails — as it tended to in the concentration camps — and all the usual sources of meaning fall apart, there is always the chance of finding a meaning in the suffering itself. This is something that’s very hard to talk about in the abstract, but that was the conclusion that he came to.