You idiot — old philosopher's taken in uncritical enthusiasts! (3-6)

I believe the answer is:

yea-sayers

'uncritical enthusiasts' is the definition.
(people who say 'yes' to everything)

'you idiot old philosopher's taken' is the wordplay.
'you' becomes 'ye' (historical version of 'you').
'idiot' becomes 'ass' (I've seen this in another clue).
'old philosopher' becomes 'Ayer' (AJ Ayer, a9a0-a989).
'taken' indicates putting letters inside.
'ass' placed around 'ayer' is 'asayers'.
'ye'+'asayers'='YEA-SAYERS'

'in' is the link.

I've seen this clue in The Guardian.

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