In the fields of philosophy, the terms obscurantism and obscurationism identify and describe the anti-intellectual practices of deliberately presenting information in an abstruse and imprecise manner with the intention of limiting further inquiry and understanding of a subject. The two historical and intellectual denotations of obscurantism are: (1) the deliberate restriction of knowledge — opposition to the dissemination of knowledge; and (2) deliberate obscurity — a recondite style of writing characterized by deliberate vagueness.

In the 18th century, Enlightenment philosophers applied the term obscurantist to any enemy of intellectual enlightenment and the liberal diffusion of knowledge. In the 19th century, in distinguishing the varieties of obscurantism found in metaphysics and theology, from the "more subtle" obscurantism of the critical philosophy of Immanuel Kant and of modern philosophical skepticism, Friedrich Nietzsche said that: "The essential element in the black art of obscurantism is not that it wants to darken individual understanding, but that it wants to blacken our picture of the world, and darken our idea of existence."