Isaac Newton Quotes

We know truth when we see it, from opinion, as we know when we are awake that we are awake.

Belief and knowledge are considered to be two different things. But they are not.

A thousand probabilities don't make one fact.

In practical life we are compelled to follow what is most probable ; in speculative thought we are compelled to follow truth. A man would perish of hunger and thirst, if he refused to eat or drink, till he had obtained positive proof that food and drink would be good for him. But in philosophic reflection this is not so. On the contrary, we must take care not to admit as true anything, which is only probable. For when one falsity has been let in, infinite others follow.

In truth, opinion may be taken for understanding; understanding cannot be taken for opinion. How so? Surely because opinion may be deceived; understanding cannot be. If it could, it would not be understanding but opinion. For true understanding has not only certain truth, but the knowledge of truth.

Knowing and assuming are two different things.

No amount of belief makes something a fact.

Guessing isn't knowing.

Some men are just as sure of the truth of their opinions as are others of what they know.

Guessing a thing ain't knowing a thing.

If faith is what you have to go on, if faith is the link between your beliefs and the world at large, your beliefs are very likely to be wrong. Beliefs can be right or wrong. If you believe you can fly, that belief is only true if indeed you can fly. Somebody who thinks he can fly, and is wrong about it, will eventually discover there's a problem with his view of the world.

The things of which we want the proof are those we know the best.

If you know, say you know. If you don't know, say you don't know.

All proofs inevitably lead to propositions which have no proof! All things are known because we want to believe in them.

Truth is that which cannot be proved false.

There is no permanence in doubt; it incites the mind to closer inquiry and experiment, from which, if rightly managed, certainty proceeds, and in this alone can man find thorough satisfaction.

The moment you know you know you know.

Ignorance cannot always be inferred from inaccuracy; knowledge is not always present.

You must learn all things, both the unshaken heart of persuasive truth, and the opinions of mortals in which there is no true warranty.

Is not the truth the truth?

Seeing is believing and believing is knowing and knowing beats unknowing and the unknown.

All the followers of science are fully persuaded that the processes of investigation, if only pushed far enough, will give one certain solution to each question to which they can be applied.... This great law is embodied in the conception of truth and reality. The opinion which is fated to be ultimately agreed to by all who investigate is what we mean by the truth, and the object represented in this opinion is the real.

I don't want to believe. I want to know.

If we are ready to tolerate everything as understood, there is nothing left to explain; while if we sourly refuse to take anything, even tentatively, as clear, no explanation can be given.

To know is always better, no matter what the answer might be.