Eminent scientists going off the rails is not unknown, but this 1933 Nobelist [Erwin Schrödinger] was merely making what should have been a modest claim: that the equation for which he had been awarded the prize was a true description of the facts. Schrödinger felt the need to be defensive not because he had interpreted his equation irrationally but precisely because he had not.
How could such an apparently innocuous claim ever have been considered outlandish? It was because the majority of physicists had succumbed to bad philosophy: philosophical doctrines that actively hindered the acquisition of other knowledge. Philosophy and fundamental physics are so closely connected —despite numerous claims to the contrary from both fields— that when the philosophical mainstream took a deep nosedive during the first decades of the 20th century, it dragged parts of physics down with it.
The culprits were doctrines such as logical positivism ("If it's not verifiable by experiment, it's meaningless"), instrumentalism ("If the predictions work, why worry about what brings them about?") and philosophical relativism ("Statements can't be objectively true of false, only legitimized or delegitimized by a particular culture"). The damage was done by what they had in common: denial of realism, the commonsense philosophical position that the physical world exists and that the methods of science can glean knowledge about it.
(David Deutsch and Artur Ekert, Beyond the Quantum Horizon, Scientific American September 2012, vol. 307, no 3, p.75)
To a mathematician, it's something of a shock to learn there is a doctrine called "philosophical relativism" referring to culture in order to deny the existence of universal truths, and that it dates from the first decades of the 20th century! I was of course aware of today's omnipresent, fashionable, politically correct and reality denying cultural relativism. You know, Who are we, to...? Yes, indeed, who are we not to welcome cultural enrichment by venerable ancestral traditions like cannibalism and sexual mutilation of women? Now I learnt there is more to it than post-colonial western guilt, that it is much older, and in part responsible for the interpretation of quantum physics which makes you doubt whether the moon is still there when you look away from it. Here (a paper from Man, New Series, Vol. 1, No. 3, Sep. 1966, pp. 368-374, published by The Royal Anthropological Institute of Great Britain and Ireland) you can learn more about different kinds of relativism.