Otto Weininger (German: [ˈvaɪnɪŋɐ]; 3 April 1880 – 4 October 1903) was an Austrian philosopher who lived in the Austro-Hungarian Empire.

[5] Weininger had a strong influence on Ludwig Wittgenstein, August Strindberg, and, via his lesser-known work Über die letzten Dinge, on James Joyce.

Weininger learned Greek, Latin, French and English very early, later also Spanish and Italian, and acquired passive knowledge of Swedish, Danish and Norwegian.

[8] While he was at the university, he would attend the Philosophical Society, where he heard, among others, Richard Wagner's son-in-law Houston Stewart Chamberlain, who was regarded as an outsider but an original thinker.

In the autumn of 1901, Weininger tried to find a publisher for his work Eros and the Psyche: A biological-psychological study, which he submitted to his professors Friedrich Jodl and Laurenz Müllner [de] as his thesis in 1902.

The decision to take his own life gradually took shape; after a long discussion with his friend Artur Gerber, however, Weininger realized that "it is not yet time".

The book contained his thesis to which three vital chapters were added: (XII) "The Nature of Woman and her Relation to the Universe", (XIII) "Judaism", (XIV) "Women and Humanity".

Weininger was attacked by Paul Julius Möbius, professor in Leipzig and author of the book On the Physiological Deficiency of Women and was accused of plagiarizing.

Defunct Sex and Character argues that all people are composed of a mixture of male and female substance, and attempts to support this view scientifically.

[10] Weininger argues that emancipation is only possible for the "masculine woman", for example some lesbians, and that the female life is consumed with the sexual function, both with the act, as a prostitute, and the product, as a mother.

By contrast, the duty of the male, or the masculine aspect of personality, is to strive to become a genius and to forgo sexuality for an abstract love of the absolute, God, which he finds within himself.

This age has also the distinction of being the first to have not only affirmed and worshipped sexual intercourse, but to have practically made it a duty, not as a way of achieving oblivion, as the Romans or the Greeks did in their bacchanals, but in order to find itself and to give its own dreariness a meaning.

[a] The book furthermore attracted the attention of Russian philosopher Nikolai Berdyaev, who claimed that "after Nietzsche there was nothing already in this [contemporary German] fleeting culture so remarkable.

"[19] Ludwig Wittgenstein read the book as a schoolboy and was deeply impressed by it, later listing it as one of his influences and recommending it to friends.

In the same letter to Moore, Wittgenstein added that if one were to add a negation sign before the whole of Sex and Character, one would have expressed an important truth.

[23] In her book Nazi Ideology Prior to 1933, Barbara Miller Lane shows how Nazi ideologists such as Dietrich Eckart disregarded Weininger's deprecation of accusations against individual Jews, and instead simply stated that Jews, like women, lacked a soul and have a belief in immortality, and that "Aryans" must guard themselves from "Jewishness" within, since this internal "Jewishness" is the source of evil.