ONE final point: expert opinion is not a substitute for intellectual reflection. Call them men (and women) of letters, intellectuals, generalists or polymaths. Since the Renaissance the intellectual and cultural life of a society depends on people who are able to transcend the limits of specialisation and have a grasp of the big picture. This point was clearly grasped in the 19th century by thinkers who were concerned about the consequences of excessive specialisation on public life. Writing in 1849, G.L. Lewis warned "that men of comprehensive minds should survey the whole circle of the sciences, should understand their mutual relations" so as "to avoid that narrowing influence which is produced by restricting the mind to the exclusive contemplations of one subject".

Since the 19th century, the problem of narrow specialisation and the erosion of a genuine dialogue across the arts and sciences has been widely commented on. In 1959, C.P. Snow expressed his anxiety about the split of intellectual life into the two cultures of the arts and sciences. How would he respond to the situation today when the two cultures have given way to disciplinary insularity within science and arts, where philosophers can't talk to historians and sociologists can't have a conversation with economists? What we need are not more experts but thinkers and commentators who can interpret the meaning that different forms of knowledge has for society.

A bit on the dense side, but well worth the read. This is relevant to the process of design in that individuals from all manner of specializations – cough, UX, QA, and legal, cough – are prone to jump from providing dispassionate technical information on a question to making judgements based on opinions and valuations that are completely outside the scope of their expertise.