In 1937 the German existentialist philosopher Karl Jaspers gave a final public lecture before being silenced under the Nazi regime. He spoke of radical paradigm shifts in the natural sciences in the early 20th century -- the emergency of quantum theory, for example -- that had seriously undercut the absolutist pretensions of 19th century scientific positivism to explain everything about the world with complete objectivity. He then said this:
Analogous though less magnificent phenomena occurred everywhere in the special sciences. Every absolute pre-supposition collapsed. For example, the nineteenth-century dogma of psychiatry that diseases of the mind are diseases of the brain, was called into question. With the surrender of this confining dogma, the expansion of factual knowledge replaced an almost mythological construing of mental disturbances in terms of entirely unknown brain-changes. Researchers endeavored to discover to what extent mental illnesses are diseases of the brain, and learned abstain from anticipatory general judgments: while they enormously extended the realistic knowledge of man, they still did not capture man.*
* Karl Jaspers, "Introduction to Philosophy of Existence," in Richard Kearney and Maria Rainwater (eds.), The Continental Philosophy Reader (New York: Routledge, 1966), p. 58 (emphasis in the original).