In relation to any experiment we may speak of this hypothesis as the null hypothesis, and it should be noted that the null hypothesis is never proved or established, but is possibly disproved, in the course of experimentation. Every experiment may be said to exist only in order to give the facts a chance of disproving the null hypothesis.
Coinage of the phrase "null hypothesis". The Design of Experiments, Edinburgh: Oliver and Boyd, 1935, p. 18