Jean-Paul Sartre walks into a café, and the waiter asks what he’d like to order. Sartre replies, ‘I’d like a cup of coffee with sugar, but no cream.’ The waiter goes off, but comes back apologising. ‘I’m sorry, Monsieur Sartre, we are all out of cream.’ How about with no milk?’ The joke hinges on the notion that the Absence of Cream and the Absence of Milk are two definite negativities, just as Cream and Milk are two definite positivities.
