y 
THE PHILOSOPHY OE BIRDS’ NESTS 1 
Instinct or Reason in the Construction of Birds’ Nests 
Birds, 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. 
