Vv 
THE PHILOSOPHY OF BIRDS’ NESTS? 
Instinct or Reason in the Construction of Birds’ Nests 
Birps, we are told, build their nests by instinct, while man 
constructs his dwelling by the exercise of reason. Birds 
never change, but continue to build for ever on the self-same 
plan; man alters and improves his houses continually. 
Reason advances ; instinct is stationary. 
This doctrine is so very general that it may almost be 
said to be universally adopted. Men who agree on nothing 
else accept this as a good explanation of the facts. Philo- 
sophers and poets, metaphysicians and divines, naturalists 
and the general public, not only agree in believing this to be 
probable, but even adopt it as a sort of axiom that is so self- 
evident as to need no proof, and use it as the very foundation 
of their speculations on instinct and reason. A belief so 
general, one would think, must rest on indisputable facts, 
and be a logical deduction from them. Yet I have come to 
the conclusion that not only is it very doubtful, but absolutely 
erroneous ; that it not only deviates widely from the truth, 
but is in almost every particular exactly opposed to it. I 
believe, in short, that birds do not build their nests by 
instinct ; that man does not construct his dwelling by reason ; 
that birds do change and improve when affected by the same 
causes that make men do so; and that mankind neither alter 
nor improve when they exist under conditions similar to 
those which are almost universal among birds. 
1 First published in the Intellectual Observer, July 1867; reprinted in 
Contributions, etc., with considerable alterations and additions; and with 
further additions in the present volume. 
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