No single theory ever agrees with all the facts in its domain

A theory that explains everything, explains nothing

A theory is like medicine or government: often useless, sometimes necessary, always self-serving and, on occasion, lethal. It needs to be used with care, moderation and close adult supervision.

I don't think there is a final theory of anything. It's theories all the way down.

Scientific theory is a contrived foothold in the chaos of living phenomena.

Each new ontological theory, propounded in lieu of previous ones shown to be untenable, has been followed by a new criticism leading to a new scepticism. All possible conceptions have been one by one tried and found wanting; and so the entire field of speculation has been gradually exhausted without positive result: the only result reached being the negative one above stated, that the reality existing behind all appearances is, and must ever be, unknown.

No theory is good unless it permits, not rest, but the greatest work. No theory is good except on condition that one use it to go on beyond.

Every one knows that our civilization is in difficulties, and the stupidity of the suggested remedies only indicates the gravity of the disease, for a sick society has to diagnose and cure its own complaint, and the worse the complaint, the wilder the diagnosis is likely to be But no one denies the disease.

Theories that diseases are caused by mental states and can be cured by will power are always an index of how much is not understood about a disease.

I don't believe that the ultimate theory will come by steady work along existing lines. We need something new. We can't predict what that will be or when we will find it because if we knew that, we would have found it already! It could come in the next 20 years, but we might never find it.

The strength of a theory is not what it allows, but what it prohibits; if you can invent an equally persuasive explanation for any outcome, you have zero knowledge.

Once upon a time, the founder of Protestant Christianity, said that doctors were fools, for treating diseases, as if they came from material causes. Then, Louis Pasteur disproved that, and came up with something, gonna love this, he called it "Germ Theory." Germs are still a theory! Atomic Theory is still a theory. Theory of gravity has never been proved.