Carl Sagan on Philosophy

"Once intelligent beings achieve technology and the capacity for self-destruction of their species, the selective advantage of intelligence becomes more uncertain."

"Other things being equal, it is better to be smart than to be stupid."

"Human beings have a demonstrated talent for self-deception when their emotions are stirred."

"If we long to believe that the stars rise and set for us, that we are the reason there is a Universe, does science do us a disservice in deflating our conceits?"

"This doesn’t mean you can picture a billion or a quintillion objects in your head—nobody can. But, with exponential notation, we can think about and calculate with such numbers. Pretty good for self-taught beings who started out with no possessions and who could number their fellows on their fingers and toes."

"Vigorous criticism is more constructive in science than in some other areas of human endeavor because in science there are adequate standards of validity that can be agreed upon by competent practitioners the world over. The objective of such criticism is not to suppress but rather to encourage the advance of new ideas: those that survive a firm skeptical scrutiny have a fighting chance of being right, or at least useful."

"If I were to propose to you that my arm could be in this position or in that position but it would be forbidden by the laws of nature to be in some intermediate position, that would likely strike you as absurd, as contrary to experience. And yet on the subatomic level, there is a quantization of energy and position and momentum. The reason that it seems counterintuitive is that is that we are not ordinarily down at the level of the very small, where quantum effects dominate."

"We are ignorant about the complex mutual dependencies of the beings on earth, and what the sequential consequences will be if we wipe out some especially vulnerable microbes on which larger organisms depend. We are tugging at a planetwide biological tapestry and do not know whether one thread only will come out in our hands, or whether the whole tapestry will unravel before us."

"The idea that as I walk in this direction my watch goes slightly slower and I am contracted in the direction of motion and my mass has increased slightly does not correspond to everyday experience. ...the reason that it does not correspond to common sense is that we are not in the habit of traveling close to the speed of light. We may one day be in that habit, and then the Lorentz transformations will be natural, intuitive."

"St. Anselm argued that since we can imagine a perfect being, he must exist—because he would not be perfect without the added perfection of existence. This so-called ontological argument was more or less promptly attacked on two grounds: Can we imagine a completely perfect being? Is it obvious that perfection is augmented by existence? To the modern ear such pious arguments seem to be about words and definitions rather than about external reality."

"It is easy to create an interstellar radio message which can be recognized as emanating unambiguously from intelligent beings. A modulated signal comprising the numbers 1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, for example, consists exclusively of the first 12 prime numbers—that is, numbers that can be divided only by 1, or by themselves. A signal of this kind, based on a simple mathematical concept, could only have a biological origin. . . . But by far the most promising method is to send pictures."

"I had become friendly with a group of people who occasionally smoked cannabis, irregularly, but with evident pleasure. Initially I was unwilling to partake, but the apparent euphoria that cannabis produced and the fact that there was no physiological addiction to the plant eventually persuaded me to try. My initial experiences were entirely disappointing; there was no effect at all, and I began to entertain a variety of hypotheses about cannabis being a placebo which worked by expectation and hyperventilation rather than by chemistry. After about five or six unsuccessful attempts, however, it happened."

"It seems to me 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 the useful ideas from the worthless ones."

"Now, there has been the view that ... if there is nothing special about us in space then maybe there is something special about us in time. ... To me, the principal trouble with this idea is that 99.998% of the lifetime of the universe, from its beginning to now, was over before humans appeared on the scene."

"I would love to believe that when I die I will live again, that some thinking, feeling, remembering part of me will continue. But much as I want to believe that, and despite the ancient and worldwide cultural traditions that assert an afterlife, I know of nothing to suggest that it is more than wishful thinking. The world is so exquisite with so much love and moral depth, that there is no reason to deceive ourselves with pretty stories for which there's little good evidence. Far better it seems to me, in our vulnerability, is to look death in the eye and to be grateful every day for the brief but magnificent opportunity that life provides."