system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What philosophical concept is Sartre alluding to?

There is a famous anecdote Sartre (I think it was Sartre) used to explain some philosophical concept. Roughly, he describes a person ordering a coffee without cream. The waiter explains that they don't have any cream, but they can make a coffee without milk.

What exactly is this analogy alluding to? What is the philosophical idea behind it? Something about negatives or absence?
gpt
Sartre was into phenomenology, looking at ideas of conscious experience. In opposition to certain other philosophical schools that held "being" and "existence" as the absolute measure of something, Sartre held the perspective that negation and absence are also concrete realities and experiences in and of themselves. For example, if a loved one is absent and you miss them, their absence is not just a lack of presence, it is a separate and specific experience. He wrote a book called *Being and Nothingness* on this topic.

The joke in question takes this philosophical position to an absurd extreme, proposing that the deliberate absence of cream is its own specific experience, distinguished from an involuntary absence of cream due to lack of availability. In this world, the absence of milk is a different experience than the absence of cream, so the waiter needs to ask if it is an acceptable substitute.