Full Idea
There is no reason to suppose that the meaning of 'know' changes from the courtroom to the living room and back again; no more than for supposing that 'vacuum' changes from the laboratory to the cannery.
Gist of Idea
The meaning of 'know' does not change from courtroom to living room
Source
Peter Unger (Ignorance: a Case for Scepticism [1975], 2.1)
Book Reference
Unger,Peter: 'Ignorance: a Case for Scepticism' [OUP 1975], p.53
A Reaction
I disagree. Lots of words change their meaning (or reference) according to context. Flat, fast, tall, clever. She 'knows a lot' certainly requires a context. The bar of justification goes up and down, and 'knowledge' changes accordingly.