METHOD OF MULTIPLE WORKING HYPOTHESES 839 
able at a later stage, ‘‘ How came this so?”’ First the full facts, 
then the interpretation thereof, is the normal order. 
The habit of precipitate explanation leads rapidly on to the 
birth of general theories.t When once an explanation or spe- 
cial theory has been offered for a given phenomenon, self-con- 
sistency prompts to the offering of the same explanation or 
theory for like phenomena when they present themselves and 
there is soon developed a general theory explanatory of a large 
class of phenomena similar to the original one. In support of 
the general theory there may not be any further evidence or 
investigation than was involved in the first hasty conclusion. 
But the repetition of its application to new phenomena, though 
of the same kind, leads the mind insidiously into the delusion 
that the theory has been strengthened by additional facts. A 
thousand applications of the supposed principle of levity to the 
explanation of ascending bodies brought no increase of evidence 
that it was the true theory of the phenomena, but it doubtless 
created the impression in the minds of ancient physical philoso- 
phers that it did, for so many additional facts seemed to harmo- 
nize with it. 
For a time these hastily born theories are likely to be held 
in a tentative way with some measure of candor or at least some 
self-illusion of candor. With this tentative spirit and measur- 
able candor, the mind satisfies its moral sense and deceives itself 
with the thought that it is proceeding cautiously and impartially 
toward the goal of ultimate truth. It fails to recognize that no 
amount of provisional holding of a theory, no amount of applica- 
tion of the theory, so long as the study lacks in incisiveness and 
exhaustiveness, justifies an ultimate conviction. It is not the 
slowness with which conclusions are arrived at that should give 
satisfaction to the moral sense, but the precision, the complete- 
ness and the impartiality of the investigation. 
*T use the term theory here instead of hypothesis because the latter is associated 
with a better controlled and more circumspect habit of the mind. This restrained 
habit leads to the use of the less assertive term hypothesis, while the mind in the habit 
here sketched more often believes itself to have reached the higher ground of a theory 
and more often employs the term theory. Historically also I believe the word theory 
was the term commonly used at the time this method was predominant. 
