“The functional validity of a working hypothesis is not a priori certain, because often it is initially based on intuition. However, logical deductions from such a hypothesis provide expectations (so called prognoses) as to the circumstances under which certain phenomena will appear in nature. Such a postulate or working hypothesis can then be substantiated by additional observations or by experiments especially arranged to test details. The value of the hypothesis is strengthened if the observed facts fit the expectation within the limits of permissible error.”

“Have the climate models been successful in predicting anything? They, of course, predict substantial global warming. This is not surprising given the expressed belief of some of the model builders in the global warming hypothesis and the many parameters in the model that need to be introduced. However, the models also predict unambiguously that the atmosphere is warming faster than the surface of the earth; but all the available observational data unambiguously shows the opposite! Truth in science is always determined from observational facts. One finds the truth by making a hypothesis and comparing observations with the hypothesis. It is absolutely essential that one should be neutral and not fall in love with the hypothesis. If the facts are contrary to any predictions, then the hypothesis is wrong no matter how appealing. "Truth by Assertion" is not science.”

“Although to penetrate into the intimate mysteries of nature and thence to learn the true causes of phenomena is not allowed to us, nevertheless it can happen that a certain fictive hypothesis may suffice for explaining many phenomena.”
Quanquam nobis in intima naturae mysteria penetrare, indeque veras caussas Phaenomenorum agnoscere neutiquam est concessum: tamen evenire potest, ut hypothesis quaedam ficta pluribus phaenomenis explicandis aeque satisfaciat, ac si vera caussa nobis esset perspecta.

“The usefulness of observation and measurement in testing economic theories arises because the theorems of economics are supposed to relate to the actual world… Any economic theorem rigorously deduced from given postulates may be regarded as a hypothesis about the actual world which xperience may show to be false.”

“(Coining phrase "null hypothesis") 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.”

“In other words, the fundamental principles and indispensable postulates of every genuinely productive science are not based on pure logic but rather on the metaphysical hypothesis — which no rules of logic can refute — that there exists an outer world which is entirely independent of ourselves. It is only through the immediate dictate of our consciousness that we know that this world exists. And that consciousness may to a certain degree be called a special sense.”

“The hypothesis that human emissions of CO2 can create global warming can be tested by measurement. … No warming has occured since 1998. … During that time atmospheric CO2 has increased. … The test of the hypothesis above shows that there is no relationship between measured temperature and CO2 emissions. The hypothesis fails.”

“The atomic hypothesis which had worked so splendidly in Physics breaks down in Psychics.”

“It is possible to express the laws of thermodynamics in the form of independent principles, deduced by induction from the facts of observation and experiment, without reference to any hypothesis as to the occult molecular operations with which the sensible phenomena may be conceived to be connected; and that course will be followed in the body of the present treatise. But, in giving a brief historical sketch of the progress of thermodynamics, the progress of the hypothesis of thermic molecular motions cannot be wholly separated from that of the purely inductive theory.”

“The day of the last hypothesis would be also the day of the last observation… An hypothesis displaced by new facts dies an honorable death. If it has itself summoned to its trial the facts by which it is annihilated, it deserves even a monument of gratitude.”