The best causes tend to attract to their support the worst arguments, which seems to be equally true in the intellectual and in the moral sense.

Natural selection is not evolution.

In scientific subjects, the natural remedy for dogmatism has been found in research.

We can set no limit to human potentialities; all that is best in man can be bettered; it is not a question of producing a highly efficient machine, ... but of quickening all the distinctly human features, all that is best in man, all the different qualities, some obvious, some infinitely subtle, which we recognize as humanly excellent.

Experimental observations are only experience carefully planned in advance, and designed to form a secure basis of new knowledge.

Inductive inference is the only process known to us by which essentially new knowledge comes into the world.

We have usually no knowledge that any one factor will exert its effects independently of all others that can be varied, or that its effects are particularly simply related to variations in these other factors.