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

... the actual and physical conduct of an experiment must govern the statistical procedure of its interpretation.

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.

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.

To consult the statistician after an experiment is finished is often merely to ask him to conduct a post mortem examination. He can perhaps say what the experiment died of.

We may consequently state the fundamental theorem of Natural Selection in the form: The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time.

If ... we choose a group of social phenomena with no antecedent knowledge of the causation or absence of causation among them, then the calculation of correlation coefficients, total or partial, will not advance us a step toward evaluating the importance of the causes at work.