You are correct that a theory is not a law, however the common use of phrases such as "its just a theory" used with regard to scientific theory illustrate that the meaning of theory as used in science is not understood by a great number of people.
About once a year we go to a particular relative’s house (once in a while they come to us) and every year it is a bit like Bill Murray’s Groundhog Day. These relatives of ours (who strangely are on my wife’s side) do not believe in things like evolution and so on.
“I mean it is a theory! It says so right in the title – The Theory of Evolution. If it was a law they would call it the Law of Evolution…”
BTW (and this might sound like a strange statement), these relatives of ours, in a sense, don’t really view their account of creation as a religious matter. To them it is a historical account from a source that they trust.
In a sense I can understand where they are coming from and I feel that I should respect what they might refer to as their “secular” perspective on this specific matter. (I’m not sure what other word to use here).
Consider the following. If someone approached you and said:
• Don’t kill people
• Don’t steal their stuff
• And Don’t sleep with my spouse
Most of us are willing to accept this advice in its plain and simple context. My guess is that you are going say/think something like “Well that sounds like pretty good advice”. I doubt that most people are going to reject it because they believe that they can establish an association of it to some religious reference.
I suppose that what I am saying is this.
I find it annoying/frustrating in discussions when the vernacularized sense of the term Theory is used to construct what in reality is a weak argument against a particular scientific belief; However, I don’t automatically dismiss or hold in contempt people who do not agree with me as to when something should be viewed through the lenses of generally accepted scientific principles.
In some cases I only try to get an acknowledgement that a particular view that they hold, while perfectly acceptable to hold within a faith based system, is none-the-less not science. Sometime I succeed, sometimes I don’t.
I should point out, that these relatives of ours, are very nice, gentle and caring people. I really don’t mind going through “the routine” once a year. It is usually fun. And in some years, towards the end of our stay, I actually see them give ground and start to consider some of what I say. (I worry about their kids though. They are home schooled and I wonder in what manner they will function in a modern world.)
But getting back to the main point, the scientific/academic community has not always maintained consistency in the usage of the terms (or perhaps just explaining them) over I guess what would be centuries.
I have a pet hypothesis (note that I didn’t say theory) that sometimes scientists have perhaps chosen one term over the other based on contemporaneous perceptions of relative prestige. (I also have a competing pet hypothesis that if you are on the lower end of the Department’s organizational chart, your Department Chair is not going to let you use the term Law on anything).
I ran across this story a few years ago. A famous mathematician from the 1940s and 50s, John von Neumann provided the following advice to Claude Shannon. (Some people consider him to be the founding father of the electronic communication age
https://www.youtube.com/watch?v=z2Whj_nL-x8). Anyway I thought that the quote was memorable.
“You should call it entropy, for two reasons. In the first place your uncertainty function has been used in statistical mechanics under that name, so it already has a name. In the second place, and more important, no one really knows what entropy really is, so in a debate you will always have the advantage.”
- John von Neumann
http://www-history.mcs.st-andrews.ac.uk/Biographies/Von_Neumann.htmlhttp://www-history.mcs.st-andrews.ac.uk/Biographies/Shannon.htmlThe point is that scientists and academics are not immune from the temptations of what might be called the “marketing” of their ideas.
Anyway, I came across a definition and discussion of the terms by a Professor Ronald Matson. I was impressed with his thoughts.
.
http://science.kennesaw.edu/~rmatson/3380theory.htmlOne quick definition he provides:
• A law describes
what nature does under certain conditions, and will predict what will happen as long as those conditions are met.
• A theory explains
how nature works.
There is more on the site.