Read this quote,
"The man who has no tincture of philosophy goes through life imprisoned in the prejudices derived from common sense, from the habitual beliefs of his age or his nation, and from convictions which have grown up in his mind without the cooperation or consent of his deliberate reason. To such a man the world tends to become definite, finite, obvious; common objects rouse no questions, and unfamiliar possibilities are contemptuously rejected. As soon as we begin to philosophize, we find, that even the most everyday things lead to problems to which only very incomplete answers can be given."
It is by Bertrand Russell and I found it here. Italics are my own.
To put it slightly differently, doesnt it mean that those who philosophize find problems in the most everyday things, and generally lack common sense?
Maybe there is more to Permanent Head Damage theory than meets the eye!