Sartre was atheist, but was strongly against determinism; an argument of his against the existence of God was that God's existence is incompatible with human freedom. I have been wondering about whether it is possible to be an atheist and not to be a determinist, so I have been doing some reading lately on determinism vs. free will and there is just a boundless selection of theories and ideas to think through. However, from what I've read, I would mostly consider myself to be a libertarian, and if I understand it correctly libertarianism is the view that humans are unmoved movers; we can will to do event A (leave a room), refrain from willing to do event A, or will to do event B, without anything being different inside or outside of our being; "[We are] the absolute originator[s] of [our] own actions"(1). This position is in contrast to various other views, such as hard/soft determinism and hard/soft compatibilism, all of which, I would find no surprise, probably can be separated into even more categories.
So Sartre, being an atheist, would not believe in any type of "super"nature, which could be described as anything acting outside of what C.S. Lewis calls the "Total System" of events, or "The Whole Show"(2). Every event in nature is caused, and our acts of thinking, being events, would be caused by the previous effect of a cause, which is the effect of the cause before it, and this would span out from the beginning to the end of time. So in this sense, without the human as a first mover of his thoughts, our thoughts and actions are pretty much determined. Now from what I've read, a compatibilist will agree to this, yet still say that humans can have freedom of the will. Our desires may be determined, but we are free to will whatever we desire. To be honest I'm not sure if an atheist can hold this position because there is really no explanation as to why our desires are determined but not our willing to do them (is "willing to do" something an "act"?).
I'm willing to think, then, that Sartre was not a libertarian, and possibly was more on the compatibilist side, but with my little knowledge of Sartre and the theories of freedom he could be in a hundred different positions. I just think that if Sartre was a naturalist, and if naturalism (meaning that "every finite thing or event must be (in principle) explicable in terms of the Total System"(3)) leaves no room for free will, then his "existence precedes essence" dictum, which Cooper sums up with "Existence now precedes essence in that how a person is at a given time results from the free decisions he has made," seems to be not as "uplifting" as it's described (4). Our essence would be just as determined as our existence is. Cooper also brings up the point that Sartre was complaining about the "pervasive tendency to employ terms...for labelling and pigeon-holing people [and] the tendency to suppose that once [a person] has been classified...we have 'summed him up'" (5). He goes on to say that we can rise above what we've been defined as and "direct how [we] shall become." This could be possible in certain cases (assuming we have free will), but one thing that really defines all humans is that we're all "sinners", and if we don't want to use religious language here, instead of saying "sinners" we could say that there is a standard that we all know is there throughout our whole lives that we cannot live up to. Everyone will lie knowing full well that it's wrong, and they will
not want to lie at that instant but do it anyways because that is our nature, a thing that we cannot rid ourselves of. Maybe we will quit lying, but it comes up in other scenarios; adultery, stealing, cheating, gossiping, etc. It almost seems that it is an essence of ours that in these scenarios our reason will fight our passion till the end, and never conquer it.
(1). J.P. Moreland and William Lane Craig, "Philosophical Foundations for a Christian Worldview," 270.
(2). C.S. Lewis, "Miracles," 17.
(3). Ibid.
(4). David E. Cooper, "Existentialism: A Reconstruction," 69.
(5). Ibid.
