In “Nausea” (“La Nausée”), a novel in the form of a fictional diary, Sartre makes the main character, the diarist, Roquentin, realize how baseless our assumptions about what is possible, what can happen in our world, or what gives the world its regularity, really are. For example:
I got up. I could no longer keep my place in the midst of these unnatural objects. I went to the window and glanced out at the skull of Impetraz. I murmured: Anything can happen, anything. But evidently, it would be nothing horrible, such as humans might invent. Impetraz was not going to start dancing on his pedestal: it would be something else entirely.
Frightened, I looked at these unstable beings which, in an hour, in a minute, were perhaps going to crumble: yes, I was there, living in the midst of these books full of knowledge describing the immutable forms of the animal species, explaining that the right quantity of energy is kept integral in the universe; I was there, standing in front of a window whose panes had a definite refraction index. But what feeble barriers! I suppose it is out of laziness that the world is the same day after day. Today it seemed to want to change. And then, anything, anything could happen.
But if everything is metaphysically contingent, why should we think that “anything can happen”? Between
- simple “not existing but contingently so”, like a full size replica of the Eiffel tower made of plastic
- “metaphysically necessarily impossible” (like tiling an – Euclidean 2D – bathroom floor with regular pentagons),
there is still
- “impossible by the laws of nature”, like a combustion engine made of paper with origami.
It obviously seems 2. and 3. are not real for Sartre. But does he justify the connection of 2. and 3. anywhere?