The following is a verbal statement of Newton’s law of universal gravitation: “Any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.”

In contrast, the mathematical formula expressing Newton’s law of universal gravitation looks like this:

   

                                                                                

And now consider another example:

                                                         

                                                     

The Pythagorean theorem is a mathematical law, but is it a scientific one? Can it be tested in some absolutely unshakable way in the real world? (Hint: How can you measure the sides and know you’re exactly accurate?)

The big problem occurs when we try to analyze logically just how true statements like Newton’s laws of motion or Darwin’s theory of evolution are. Do statements of these laws express unshakable truths about the real world or are they just temporarily useful ways of roughly describing what appears to be going on in reality – ways that are followed for a few decades while the laws appear to work for scientists, but that then are revised or dropped when new problems the law can’t explain are encountered?

Many scientific theories in the last four hundred years have been revised or dropped altogether. Do we dare to say about any natural law statement that it is true in the unassailable way in which 5 + 7 = 12 is true or the Pythagorean theorem is true?

This debate is a hot one in Philosophy right up to the present time. Many philosophers of Science claim that natural law statements, once they’re supported by enough experimental evidence, can be considered to be true in the same way as valid Math theorems are. But there are also many who say the opposite —that all scientific statements are tentative. These people believe that, given time, all such statements get replaced by new statements based on new models or theories (as, for example, Einstein's Theory of Relativity replaced Newton's laws of motion and gravitation). 

If all generally accepted natural law statements are seen as being only temporarily true, then Science can be seen as a kind of fashion show whose ideas have a bit more shelf life than the fads in the usual parade of tv shows, songs, makeup, and hairstyles. In short, Science’s law statements are just more narratives, not necessarily true so much as useful, but useful only in the lands in which they gain some currency and only for limited time periods at best.