The Cosmos would be a sorry little affair if it did not
offer something for every age to investigate. [Seneca]

Carl Sagan, author of the book and PBS television series Cosmos, was a determined, energetic advocate of science. His statement that "I don't want to believe. I want to know." is a good example of why scientists set belief and disbelief aside to examine claims with skepticism and conclusions with evidence.

Scientists do not debunk evidence that conflicts with their conclusions. They change their conclusions to fit the evidence. Scientists reason their way to conclusions with inductive, evidence-based thinking, not with deductive, belief-based opinions or predictions. Scientists don't judge a book by its cover. They open it and start reading.

Science matters in many ways, some more important than others. It mattered thousands of years ago when the Egyptians built pyramids and when the Greeks enlarged our understanding of art, mathematics and the shape of our world. It mattered in negative ways during the Dark Ages when mankind turned away from art and science. During the Renaissance, when mankind once again embraced art and science, it mattered in positive ways. During the Industrial Revolution of the 19th century, science took giant steps forward as mankind discovered ways to mechanize transportation, build factories and make life easier and less subject to disease.

Today, scientific research and development is the heart of advances in technology that men and women only a few hundred years ago would have thought of as magic. Some applications of science are not specifically focused on improving our lives with labor-saving devices. Space exploration, for example, is sometimes regarded as a waste of time, money and resources. People tend to forget or not know, however, that many of the technological advances in medicine, manufacturing and so forth were born by research that began with the passion to find ways to travel to the stars.

Some reject the claim that science will eventually abolish the gaps in what we don't know as it advances our understanding. Scientific knowledge is based on empirical evidence and natural laws, not the capricious whims of hearsay, opinions, predictions, anecdotal stories or guesses. But it is necessarily asymptotic because science can never completely eliminate what we don't know.

We do, however, tend to accept what science claims without verifying the facts ourselves. Most of us don't think about the physics behind the internal combustion engine, for example. We put the key in the ignition, turn it, and the engine roars to life. And that's not treating science like religion because everyone can apply scientific facts to their lives and see the same results. Scientific facts are repeatable because they are grounded in natural laws. Science knows, for example, the temperature at which water boils at sea level, and everyone on the beach can arrive at the same conclusion: 212 degrees Fahrenheit.

Rules can be based on deductive or inductive reasoning. Deductive reasoning is a top-down, general-to-specific process that proceeds from a general rule to a specific application of the rule. Non-skeptics tend to use deductive reasoning because they are not curious, as skeptics are, about how things really operate. An example would be, "All men are stupid. You are a man, so you are stupid." And that puts the rule above the evidence.

Inductive reasoning is a specific-to-general process that proceeds from the results of specific tests to a rule that is general because it can be applied to all cases with the same conditions. An example would be, "Every time we reward the mice with food, they run the maze faster than they did when they were not rewarded. So our conclusion is that a reward increases their problem-solving skills." And that puts the rule below the evidence.

As you can see, conclusions derived from skeptical, inductive reasoning tend to be dynamic and relative because scientific rules follow the evidence. Whereas conclusions that result from deductive reasoning tend to be static, absolute and wrong because deductive rules are just beliefs assumed to be true.

Science is not, however, an exclusively inductive process. Scientists frequently use deduction as a framework for their inductive research. A scientist, for example, might begin research by asking a deductive What if? question to give him a context for the specific tests he needs to perform to see if the results agree with the original proposition. If they do, he is justified in identifying the results as a scientific theory. A Christmas tree, for example, provides a framework for all those beautifully colored ornaments to give them a common purpose.

A jigsaw puzzle offers the same insights. You don't put each piece where it belongs on your first try. And the picture on the cover of the box gives you a context for assembling all those oddly shaped pieces. So you examine them many times, integrating information one bit at a time until you discover how they fit together to paint that complete picture.