But of course we now know that Newton’s theory of gravity is not fully correct. It has serious deficiencies such as assuming “action at a distance” (i.e., instantaneous transmission of information), ignoring relative motion constraints and the possible curvature of space not to mention the possible existence of dark matter, dark energy, and black holes. Do these deficiencies invalidate its inclusion in the class of convincing scientific theories? The answer is a resounding NO! Within its realm of validity Newton’s theory of gravity is convincing. And that realm of validity is as a useful and practical approximation to the special theory of relativity and Einstein’s general theory of relativity.

This illustrates an important point, no scientific theory is ever complete. It is always an approximation of reality but as we learn and progress over the years we get closer and closer to describing physical reality. Convincing scientific theories provide our best explanation of reality within their realms of validity.

Now that we know what is a convincing scientific theory we can explain what is a scientific law. Scientific laws are nothing more than concise expressions of the postulates (i.e., assumptions) from which a convincing scientific theory can be logically derived. Some of these laws you may be familiar with such as the conservation of mass or perhaps Newton’s three laws leading to his theory of motion and gravity.

By dint of observation and experiment scientific laws have been shown to have universal applicability but this doesn’t mean they are immutable. Just as a convincing scientific theory is probably an (very good) approximation to reality, scientific laws sometimes have to be modified as new observational knowledge is acquired. Thus the law of conservation of mass and the conservation of energy laws had to be combined and generalized to be the conservation of mass plus energy. Some laws such as the conservation of momentum actually turn out to be more fundamental than originally perceived. And some laws turn out to be specific examples of even more fundamental laws (i.e., Newton’s third law is really an example of a generalized Gaussian law of conservation. That’s why Newton’s force of gravity diminishes as the reciprocal of the distance squared). Thus, just like convincing scientific theories, scientific laws have realms of validity and sometimes these realms are much broader than originally perceived.

So where does this leave us in considering the phrase “It’s not a law”. As we have just seen, convincing scientific theories and scientific laws have the same validity. To assume one is somehow suspect (“It’s just a theory“) while the other somehow expresses certainty (“It’s not a law“) is not just fuzzy thinking but fundamentally wrong. Unfortunately confusion on these points is common.

Pages:
«« previous page 1 2 3 4 5 6 7 next page »»

Tags: Evolution, religion, Science

This entry was posted on Monday, May 4th, 2009 at 9:41 am and is filed under Evolution. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

this article with others.