Carl Sagan Quotes

When scientifically investigating the natural world, the only thing worse than a blind believer is a seeing denier.

The tendencies are considerably weaker in the natural sciences, which, for the past several centuries, have survived and flourished through such constant challenge, and therefore, at best, seek to encourage it. Serving the status quo in political and socioeconomic realms is a different matter.

Religion is based upon blind faith supported by no evidence. Science is based upon confidence that results from evidence - and that confidence can be modified and/or reversed by further observations and experimentation. Science approaches truth, closer and closer, by hard dedicated work. Religion already has it all decided, and it's in the book. It's dogma, unchangeable, and unaffected by reality and whatever facts we come upon in the real world.

Reason, observation, and experience; the holy trinity of science.

Science progresses best when observations force us to alter our preconceptions.

Where we have good, testable explanations, they then have to be tested, and we drop the ones that fail the tests.

I am as non-accepting of medical quackery and unscientific approaches as anybody else. I've grown up as a card-carrying scientist, and I know the power of science to answer questions, and for many questions I don't know of anything better than scientific approaches to answer them.

The ultimate court of appeal is observation and experiment... not authority.

Science, we are repeatedly told, is the most reliable form of knowledge about the world because it is based on testable hypotheses. Religion, by contrast, is based on faith. The term 'doubting Thomas' well illustrates the difference.

True science is never speculative; it employs hypotheses as suggesting points for inquiry, but it never adopts the hypotheses as though they were demonstrated propositions.

The man of science has learned to believe in justification, not by faith, but by verification.

A scientist... must accept the results of experiment, and nothing but the results of experiment.

Every great advance in natural knowledge has involved the absolute rejection of authority.

Educated guesswork' is what science is. You form hypotheses, test them against the evidence, and if they fit the evidence, you can assume you've got close to the truth.

I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I'll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence will have to be.

If there is any consistent enemy of science, it is not religion, but irrationalism.

It is astonishing to realize that until Galileo performed his experiments on the acceleration of gravity in the early seventeenth century, nobody questioned Aristotle's falling balls. Nobody said, Show Me!

Science is a mechanism, a way of trying to improve your knowledge of nature. It's a system for testing your thoughts against the universe, and seeing whether they match.

Science isn't done by consensus. It's done by rigorous testing.

Science is the acceptance of what works and the rejection of what does not. That needs more courage than we might think.

We must conduct research and then accept the results. If they don't stand up to experimentation, Buddha's own words must be rejected.

Another of the qualities of science is that it teaches the value of rational thought, as well as the importance of freedom of thought; the positive results that come from doubting that all the lessons are true... Learn from science that you must doubt the experts. As a matter of fact, I can also define science another way: Science is the belief in the ignorance of experts.

Imagination should give wings to our thoughts but we always need decisive experimental proof, and when the moment comes to draw conclusions and to interpret the gathered observations, imagination must be checked and documented by the factual results of the experiment.

Belief has no place as far as science reaches, and may be first permitted to take root where science stops.

Science is methodology. As a belief system it's disastrous.