Experts who venture “opinions” (sometimes merely their own inference of fact), outside their field of specialised knowledge may invest those opinions with a spurious appearance of authority, and legitimate processes of fact-finding may be subverted.
– High Court of Australia Chief Justice Murray Gleeson in HG v R (1999) 197 CLR 414.
These kinds of legal principles apply well beyond the courtroom. What Gleeson said rings true in everyday life and the media especially. It is precisely this phenomenon that results in crackpots like Noam Chomsky being listened to when they spout conspiratorial, pseudo-historic nonsense.
Being a decorated expert in linguistics or any other discipline does not mean that someone has any authority to speak about politics. Similarly, being a top geologist does not necessarily mean that someone will have any expertise in climate science; and being a climate scientist is not the same as being an economist.
We all need to be a little bit more skeptical about “experts” speaking outside their field of expertise – particularly when they are saying the opposite to what people who are genuinely experts in that field are talking about.