Date   : Wed, 30 Sep 2009 11:38:49 +0100
From   : adsb@... (Andrew Benham)
Subject: [OT] Coloured creatures;

David Harper wrote:

> In that was a discussion of certain aspects of basic logic, which observed 
> the equivalence of the two statements "All crows are black" and "All 
> not-black things are not crows", and this implies that you can test the 
> validity of the first statement by finding all the not-black things you can 
> and checking that they are not crows. The comment was made, though, whether 
> the discovery of a purple cow would intensify or weaken your belief that All 
> crows are black.

I remember if not this book then one very similar.  The phrase
which sticks in my mind is something like "the lazy scientist
could gain proof for his theory by not leaving his office, merely
by observing non-black objects which were not crows".

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"