Then the making of a better hypothesis becomes necessary and our method goes round its course again, as it were in a circle - but not truly in a circle, rather in a spiral, because this new cycle of development is at a higher level of understanding. Scientists are always prepared, indeed delighted, to change to new explanations if these lie closer to the known facts. Scientific truth, then, is not final. It represents the stages reached at any one time in the quest for understanding. The level of success in this quest is always to be measured by the degree of agreement between statement and fact.
Scientific truth represents the best that can be done at any moment.
It has no authority to prejudice further enquiry in the field to which it applies. The only grounds for accepting any hypothesis as being true for the purpose for which it is invented are that it works - that it does in fact serve the purpose of holding together a large number of existing facts, and predicting facts as yet unknown. This is very unlike the idea of truth as understood in other walks of life, and it is one of the distinguishing features of the scientific attitude. An experiment is a situation so arranged that the material that is being observed provides by its very behaviour its own answer to the question that is being posed. No - and so the solution of the problem is made impersonal and independent of the whim or the fancy of the person who is conducting the experiment.