Arthur Schopenhauer (1788 – 1860) was a German philosopher known for his atheism and pessimism—in fact, he is the most prominent pessimist in the entire western philosophical tradition. Schopenhauer’s most influential work, The World As Will and Representation, examines the role of humanity’s main motivation, which Schopenhauer called will. This will is an aimless striving which can never be fully satisfied, hence life is essentially dissatisfaction. Moreover, consciousness makes the situation worse, as conscious beings experience pain when thinking about past regrets and future fears.
Schopenhauer believed that desires cause suffering and, consequently, he favored asceticism—a lifestyle of negating desires or a denying the will similar to the teachings of Buddhism and Vedanta. In its most extreme form, asceticism leads to a voluntarily chosen death by starvation, the only form of suicide that is immune to moral critique according to Schopenhauer.
I have summarized and commented on his nihilism and pessimism in these previous posts:
“Summary of Arthur Schopenhauer’s, ‘On the Vanity of Existence’”
“Commentary on Schopenhauer’s ‘On the Vanity of Existence’”
“Summary of Arthur Schopenhauer’s, “’On the Sufferings of the World’”
“Commentary on Schopenhauer’s ‘On the Sufferings of the World’”
The above posts describe the basics of Schopenhauer’s philosophy, which is the most sustained defense of pessimism and nihilism of which I’m aware. In the very briefest sense, Schopenhauer claims that:
(1) existence is a mistake;
(2) there is no meaning or purpose to existence;
(3) the best thing for humans is non-existence;
(4) life is essentially suffering and suffering is evil;
(5) this is the worst of all possible worlds.