It is not what the man of science believes that distinguishes him, but how and why he believes it. His beliefs are tentative, not dogmatic; they are based on evidence, not on authority or intuition.

I don’t trust a theologian who dismisses the beauty of science or a scientist who doesn’t believe in the power of mystery.

I may be subjected to the criticism of being called ‘scientistic’ or a kind of blind believer in science who holds that science is able to solve absolutely all problems. Well, I certainly don’t believe that, because I cannot conceive that a day will come when science will be complete and achieved.

I believe that only scientists can understand the universe. It is not so much that I have confidence in scientists being right, but that I have so much in nonscientists being wrong.

Our belief is not a belief. Our principles are not a faith. We do not rely soley upon science and reason, because these are necessary rather than sufficient factors, but we distrust anything that contradicts science or outrages reason. We may differ on many things, but what we respect is free inquiry, openmindedness, and the pursuit of ideas for their own sake.

My practice as a scientist is atheistic. That is to say, when I set up an experiment I assume that no god, angel or devil is going to interfere with its course; and this assumption has been justified by such success as I have achieved in my professional career. I should therefore be intellectually dishonest if I were not also atheistic in the affairs of the world.

The answer to the question, 'What should I believe, and why should I believe it?' is generally a scientific one. Believe a proposition because it is well supported by theory and evidence; believe it because it has been experimentally verified; believe it because a generation of smart people have tried their best to falsify it and failed; believe it because it is true (or seems so). This is a norm of cognition as well as the core of any scientific mission statement. As far as our understanding of the world is concerned — there are no facts without values.

Science is the belief in the ignorance of experts.

"The word "belief" is a difficult thing for me. I don't believe. I must have a reason for a certain hypothesis. Either I know a thing, and then I know it - I don't need to believe it"

I care not for the girdings of superstition, for superstition is the bitter enemy of knowledge & true morality. Yes; it has come to this! Men who openly confess that they can form no idea of God, & only know him through created things, of which they know not the causes, can unblushingly accuse philosophers of Atheism.

We should be agnostic about those things for which there is no evidence. We should not hold beliefs merely because they gratify our desires for afterlife, immortality, heaven, hell, etc.

If you’re only sceptical, then no new ideas make it through to you. You never learn anything. You become a crochety misanthrope convinced that nonsense is ruling the world. (There is, of course, much data to support you.) Since major discoveries in the borderlines of science are rare, experience will tend to confirm your grumpiness. But every now and then a new idea turns out to be on the mark, valid and wonderful. If you’re too resolutely and uncompromisingly sceptical, you’re going to miss (or resent) the transforming discoveries in science, and either way you will be obstructing understanding and progress. Mere scepticism is not enough.

Moral scepticism can no more be refuted or proved by logic than intellectual scepticism can. When we stick to it that there is truth (be it of either kind), we do so with our whole nature, and resolve to stand or fall by the results. The sceptic with his whole nature adopts the doubting attitude; but which of us is the wiser, Omniscience only knows.

Nobody can claim himself to be practically proficient in a science and yet disdain its theory without revealing himself to be an ignoramus in his area.