We know our world and our universe through experience. From the moment we are born, we touch, taste, smell, hear, and look. In a way, science is just a more detailed way to do the same thing — learn about the universe through experience. In fact, that's the way the practices which developed into science got started. But science has come a long, long way in the centuries of human civilization.
Science is still firmly experience based. It's just that the kinds of things a scientist may be experiencing are often beyond the range of our human senses. Also, the practice of science has become very sophisticated. These two things together create an unfortunate and unnecessary barrier of confusion and fear between the "common citizen" and the world of science.
An important thing to know about science is that isn't something that you have; it's something that you do, and even more significantly, it's a way you think. Good scientific thinkers strive to be skeptical — to expect claims to be supported by evidence without becoming narrow minded. This is often a difficult balance to achieve, but many people spend their entire lives happily doing their best.
So if science is a way you think, then how does a modern scientist think?
All of modern scientific thought and practice is based on a single belief: that the universe can be explained in purely natural terms. Another way of saying the same thing is that science is based upon the assumption that the laws of chemistry and physics are constant. No "cheating" by applying miracles to solve problems you can't figure out.
The reason this is so important is that scientists consider it absolutely essential to be able to test the ideas they propose. The only tools scientists have to work with are the natural laws. If these laws can't be trusted to be consistent (whether we've figured out exactly what the laws are or not), then no test results or experimental data can ever be trusted.
All scientific concepts are tentative; there are no "proven" laws or theories. Because all laws and theories are experience based posits, they are all ultimately tentative. In fact, that's one of the most important features of any scientifically useful concept. The terms you usually hear used in this respect are "falsifiability" or "testability." All these mean is that for an idea to be scientifically respectable, there must be some way that it can be challenged. An example of a useless hypothesis would be, "God did it," because there is absolutely no way anyone could test the assertion. This relates directly to the basic assumption mentioned above. [Note, by the way, that this is not the same thing as saying that "God did it" is necessarily the wrong answer; it's just not a scientifically useful answer.]
Many people are confused on the issue of "facts." A fact is nothing more than a single, repeatable observation. Facts are important as the grist of the scientific mill, but are fairly trivial in and of themselves.
It is unfortunate that many science teachers have done a very poor job of conveying this aspect of science. Many people are led to distrust scientists because of the expectation that science deals in "just the facts, ma'am," when in fact all significant ideas in all of science are tentative.
Scientists do not accept new claims based on
Science has limitations; it's not the only problem solving system people use, and it's not the most appropriate system for some kinds of questions. All of the primary limitations on science are ultimately due to the requirement for testability.
The three major areas of limitation of science are:
Laws and Theories
Like "facts," laws and theories are generally misunderstood. Despite the implication of the word, a law is not something we are sure of. Laws are posits we have so much supportive evidence that we can safely treat them as if they are the truth. That doesn't mean that someday someone won't devise a new way of looking at things or a better measuring device which will show us that some or all of our laws are in need of adjustment. This is exactly what Einstein's insights did to some of Newton's laws.
Theories are also posits. Again, the relationship between theories and laws is not generally well understood. Theories do not "grow up" into laws; they have different purposes.
Laws describe the way in which the matter and energy of the universe have been observed to behave. For example, when the science of chemistry was in its fairly early developmental stages, people were doing a lot of experiments in which they combined different elements to see what they would get. One result of this activity was a set of "laws of chemical proportion." These were observations like, "If you get carbon to interact with oxygen, you will use up one part carbon for every two parts oxygen," or "If you get nitrogen to interact with hydrogen, you have to use three parts hydrogen for every one part nitrogen."
Because they are descriptions of behavior, and people want them to be as precise as possible, laws are often in the form of mathematical equations (as the laws above could be expressed if I wanted to freak you out).
Theories, on the other hand, attempt to explain why the laws are the way they are. As a result, theories are generally more complex and have more "working parts," so to speak, than laws do. They also are much more difficult to get polished and refined so that they reflect everything we have discovered about their subject. Theories are the working ideas of science. However, like laws, they are posits. By the time the scientific community has agreed that an idea is a theory, they have a lot of confidence in it because there's so much evidence in support of it, and because it explains so many things better than any other proposed hypothesis does.
The theory which explains our laws of chemical proportion is the atomic theory, or the theory of atomic structure. When the laws of chemical proportion were worked out, the concept of the atom didn't really exist. It was a couple of hundred years before anybody really began to get some evidence about atoms and what they were made of. Quite a few explanations for atomic structure were evaluated and discarded before our current theory was accepted because they didn't explain the laws of chemical proportion and other bodies of evidence that were building up about atomic behavior.
Finally, it is important to examine something from the very first part of this essay: Good scientists are always rational skeptics.
A rational skeptic needs to be convinced before accepting new ideas. It isn't enough that an idea seem "possible," or that "you can't prove it isn't so." The ideas that survive in science are those which explain the most information, and have the most evidence to support them. Richard Dawkins expressed the need for skepticism very eloquently when he said, "By all means, let us be open minded, but not so open minded that our brains drop out." (Richard Dawkins quote from his lecture entitled, "Science, Delusion and the Appetite for Wonder." Reports of the National Center for Science Education BBC1 Television, November 12th, 1996. )
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Updated 25 September 2004