How Do You Know?
Once you have an answer, take that assertion and repeat the question, “How do you know?” If you can come up with a response, ask the question again. Keep going until you reach a point where you cannot justify your certainty.
If you do this honestly, you can learn a lot about yourself and the world. In some cases, such as 2+2=4 or cats have four legs, you quickly come to the direct experience of the idea, either counting on your fingers or pointing to a cat and counting its legs. In other cases, you instead work your way back to trust in the observations of others. This is often true of scientific statements, since they are often based on other people’s reports of their experiments and mathematical computations.
Statements of a moral or metaphysical nature take you back to ideas that you believe but cannot justify, sometimes called faith. The main difference between faith assertions and scientific assertions, however, is that faith assertions of one group of people often contradict the assertions of other groups. Christians believe Jesus was God incarnate, while Jews believe that no man can be God incarnate. Moslems believe the Koran was inspired by God, while the Christians look to the Bible, and the Mormons to the Book of Mormon. Hindus believe in reincarnation, Christians and Moslems in an afterlife of heaven and hell. Others are certain there is no afterlife.
When we talk about how we know what we know, we are talking about epistemology, the study of knowledge. One of the important ways in which science is different from many religions is that science clearly defines a method for evaluating the truth of scientific assertions. First, scientific statements are limited to those which can be verified or falsified by some kind of observation, preferably some sort of measurement. Then experiments are performed with these observations in mind. Finally, the results, whether they verify or falsify the hypothesis, must be replicated by other observers attempting the same experiment.
A famous example of this was the idea that light waves travel through something called ether, a substance that was virtually unobservable. But if there was such an ether, then certain experiments with light waves moving in different directions would reveal different speeds for light to travel the same distance, just as airplanes take different times to travel the same distance depending on whether they have a tail wind or a head wind. Experiments were done and no difference was found. More experiments were done by others, taking care to be more and more precise in measuring the speed of light in different directions. No matter how precise the measurements, however, speed of light did not vary. Then came Einstein who asserted a new hypothesis: the speed of light will be measured the same no matter which direction one is traveling with respect to the light. He dispensed with the ether and no one seriously believes in ether anymore. Of course, Einstein’s assertion had to be tested as well before it became well accepted. (For details, search on “Michelson Morley Experiment”.)
With some religions, the situation is very different. For fundamentalist Christians, for example, just about anything they assert to be true will ultimately come down to a quote from their Bible. Ask how they know that the Bible is always right, and they will answer that it is a matter of faith. The problem is that the assertions of a fundamentalist Moslem will invariably come down to a quote from the Koran. How does he know the Koran is always right? Faith. Fundamentalist Jews would point to a different set of scriptures as the thing they know by faith. Mormons: the book of Mormon. All these assertions cannot be correct, so each one ought to acknowledge that his faith could be wrong. Fundamentalists don’t believe they are wrong, however; all the other fundamentalists are wrong in their faith. They can’t prove this, of course. They just know it.
Or, I believe, they don’t know it. They just believe it. Knowledge is tricky like that.
Another important difference between the fundamentalist faithful and the scientists is that the scientists are willing to admit that what they think they know could be wrong. Furthermore, the scientist can distinguish between things that are quite certain will not turn out to be wrong and things that could very well be wrong. It all depends on how much evidence there is for an idea. Gravity: lots of observations for over four hundred years have always found the acceleration of gravity to be a constant value of 9.8 meters per second per second. The existence of dark matter is a lot less certain, since there is only evidence that seems to require this odd type of matter that cannot be seen but exists and has mass enough to change the rotation of galaxies. It reminds one a lot of the ether.
But religions are not all like the fundamentalists. Buddhism, for example, disdains the assertion of faith. Buddha insisted that people should not believe his teaching just because they were his teachings. He insisted that people needed to experience the truth and believe it because of the experience. This is a lot like science. The main difference is that the truths of Buddhism have to be observed as part of subjective experience, unmediated by measurements or descriptions.
Confucius was also a great believer in direct experience. In his case, he believed that we must explore our own relationships with our family, friends, and neighbors to discover our essential humanity. The idea can be found in many different religions, especially the mystically inclined traditions.
There is a big difference between religions that insist that people accept certain ideas on faith and those that insist people discover the truth for themselves. While science may not attempt to make assertions about mysticism, metaphysics, or morality, it has in common with religions like Buddhism, Confucianism, and others that it values direct experience over inherited statements. That is very important to remember when studying the differences of various religions and the degree to which they state the truth about the world.