A critical approach to science calls for the abandonment of world systems, which is also a prerequisite to any philosophical apperception of being. True, the philosophical quest of being demands a familiarity with every branch of scientific inquiry. But it seems to be the hidden aim of science to attain through inquiry to a limit at which the area of nonknowledge is opened to the most lucid knowledge. For only fulfilled knowledge can lead to authentic nonknowledge. Then authentic being is revealed not in any world system built on knowledge but in fulfilled nonknowledge, which can be achieved only through scientific cognition, not without it and not before it. It is the supreme striving of knowledge to reach the point where cognition fails.

That is the idea that we all hope you have learned in studying science in school — we never explicitly say what this is, but just hope that you catch on by all the examples of scientific investigation. It is interesting, therefore, to bring it out now and speak of it explicitly. It’s a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty — a kind of leaning over backwards.

For example, if you’re doing an experiment, you should report everything that you think might make it invalid — not only what you think is right about it: other causes that could possibly explain your results; and things you thought of that you’ve eliminated by some other experiment, and how they worked — to make sure the other fellow can tell they have been eliminated.
Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can — if you know anything at all wrong, or possibly wrong — to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition.
In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another.
The first principle is that you must not fool yourself — and you are the easiest person to fool. So you have to be very careful about that. After you’ve not fooled yourself, it’s easy not to fool other scientists...
You just have to be honest in a conventional way after that.

What is called for is an exquisite balance between two conflicting needs: the most skeptical scrutiny of all hypotheses that are served up to us and at the same time a great openness to new ideas. If you are only skeptical, then no new ideas make it through to you. On the other hand, if you are open to the point of gullibility and have not an ounce of skeptical sense in you, then you cannot distinguish useful ideas from the worthless ones.

At the heart of science is an essential balance between two seemingly contradictory attitudes — an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.

I’m talking about a specific, extra type of integrity that is not lying, but bending over backwards to show how you’re maybe wrong, that you ought to have when acting as a scientist.

Compassionate curiosity about the self does not mean liking everything we find out about ourselves, only that we look at ourselves with the same nonjudgmental acceptance we would wish to accord anyone else who suffered and who needed help.

But you must love with a high, serious intimate sympathy, with a will, with intelligence, and you must always seek to know more thoroughly, better, and more.

historians must and ought to be exact, truthful, and absolutely free of passions, for neither interest, fear, rancor, nor affection should make them deviate from the path of the truth, whose mother is history, the rival of time, repository of great deeds, witness to the past, example and adviser to the present, and forewarning to the future.

It must not be forgotten that reason too needs to be sustained in all its searching by trusting dialogue and sincere friendship. A climate of suspicion and distrust, which can beset speculative research, ignores the teaching of the ancient philosophers who proposed friendship as one of the most appropriate contexts for sound philosophical enquiry.

Skeptical scrutiny is the means, in both science and religion, by which deep thoughts can be winnowed from deep nonsense.

A wise skepticism is the first attribute of a good critic.

Above all, we are in need of a renewed Enlightenment, which will base itself on the proposition that the proper study of mankind is man, and woman. This Enlightenment will not need to depend, like its predecessors, on the heroic breakthroughs of a few gifted and exceptionally courageous people. It is within the compass of the average person. The study of literature and poetry, both for its own sake and for the eternal ethical questions with which it deals, can now easily depose the scrutiny of sacred texts that have been found to be corrupt and confected. The pursuit of unfettered scientific inquiry, and the availability of new findings to masses of people by easy electronic means, will revolutionize our concepts of research and development. Very importantly, the divorce between the sexual life and fear, and the sexual life and disease, and the sexual life and tyranny, can now at last be attempted, on the sole condition that we banish all religions from the discourse. And all this and more is, for the first time in our history, within the reach if not the grasp of everyone. However, only the most naive utopian can believe that this new humane civilization will develop, like some dream of “progress,” in a straight line. We have first to transcend our prehistory, and escape the gnarled hands which reach out to drag us back to the catacombs and the reeking altars and the guilty pleasures of subjection and abjection. “Know yourself,” said the Greeks, gently suggesting the consolations of philosophy. To clear the mind for this project, it has become necessary to know the enemy, and to prepare to fight it.

We must have strong minds, ready to accept facts as they are.

The further the spiritual evolution of mankind advances, the more certain it seems to me that the path to genuine religiosity does not lie through the fear of life, and the fear of death, and blind faith, but through striving after rational knowledge.