Some time ago, I had a discussion with several friends regarding the meaning and use of the word “theory” in science. By the end of this (2-part) blog post, it is my hope that readers will be able to identify the differences between “theories”, “facts”, "interpretations of facts", and “laws of physics”, and that they will be able to pick out key words that will help them to gauge the credibility and weight of a particular idea or concept in science.
- Facts are generally produced by measurement or observation. These are things such as the sky being blue in the daytime in North America, or that it is easier to crush a clay pot than an iron one. Generally speaking, the facts themselves are considered pretty objective, in that everyone can see the outcome when a test is performed or a measurement is conducted. The caveat is that facts are usually interpreted within a specific framework. We will return to this later.
- Laws are statements that describe a phenomenon or event that occurs every time a measurement or observation is made. Generally speaking, if you hold some object at shoulder height and then open your hand and let it go, it will fall towards the ground. Laws don’t describe why the object falls toward the ground - just that it happens, over and over again. The more carefully we study dropping objects, the more detailed the law can be - we may even be able to describe how quickly it will fall, how much time it will take to reach the ground, and whether or not it will speed up as it falls. These details still don’t answer the question of why. Laws are called such because they can be reliably reproduced under a given set of circumstances. Now, if those circumstances change, eventually we can set up a situation in which these laws break down.
- A hypothesis is an untested idea or hunch about something that has been observed. Many times, these ideas arise from studying laws and making predictions about what would happen under various changes in the circumstances. A good hypothesis will be testable and falsifiable - that is, you can set up some type of experiment or search that will test the hypothesis, and they hypothesis is set up in such a way that it can be proven wrong. Often, hypotheses begin to try to answer some of the why questions surrounding laws and facts. Successful hypotheses (confirmed by experiment) can help bolster confidence that your understanding of some of the why questions is on the right track, because you were able to successfully predict what should happen in a specific case. It doesn’t necessarily prove, however, that every part of it is correct.
- A theory is a framework in which you try to make a consistent, coherent interpretation of facts and laws. It can include or inform hypotheses, but theories are not the same as hypotheses. Theory will make predictions that can be turned into hypotheses based on previous observations, facts, and laws. If tests of those hypotheses turn out to be successful, the theory gains credibility. Well-established theories have been tested over and over again, ideally by making predictions that have been shown to be correct. This does not mean that the theory is completely true, or that it will never need to be modified as new information comes to light. It can, however, show that the theory is a good framework from which a basic understanding of the underlying laws can be gained, and that it makes sense to consider the theory a reasonable interpretation of the facts.
- An interpretation of facts, in the way that I use it here, is the set of things that we assume the facts tell us, based on the coherent picture or framework or theory that we use to explain the facts. In other words, once we have collected the facts and built a reasonable theory about why they should be so, we begin to look at new facts through the lens of what they would mean in our theory.
Let’s give an example. Let us say that Jim had a birthday, and Sue baked a cake. Polly baked a cake on Elliott’s birthday. Cassidy baked a cake on Katrina’s birthday. These are facts. As a matter of fact :), by travelling from city to city, we find that in the United States of America, people often bake cakes and decorate their houses when the birthday of a family member or friend draws near. The cake is often baked on the same day as the birthday. This happens over and over again, and we’ve been able to document it. This is the birthday law. Note that we can all think of exceptions to this law, so it doesn’t hold under every circumstance - for example sickness, or conflict, or perhaps even personal beliefs or indifference. Nonetheless, there is a large number of cases with general conditions in which we find this to be true. So we call it the birthday law.
Now WHY are cakes baked on birthdays? This we do not know, and it is not included in the birthday law. We might even be able to add more information to the birthday law, making predictions of, say, the ethnicities and ages of people who bake cakes on birthdays, or where they live. We could test these hypotheses and add the new information to our description of the birthday law. But these things still doesn’t really tell us why cakes are baked on birthdays.
We can start to collect all of these hypotheses together to form a theoretical framework. In this example, we may not have all the answers to why cakes are baked on birthdays, but we can at least begin to assemble our various hypotheses and laws into a theory of birthday celebration. And I can begin to use this theory to interpret various facts: If I am in Thistown, USA, and Pedro bakes a cake with sprinkles and candles for his brother Peter, I might assume that today is Peter’s birthday. Notice that the interpretation of the facts (that the baked cake means that it is Peter’s birthday) is not quite the same as the facts themselves (the actual baked cake), and can be wrong - Peter’s birthday might be tomorrow or might have been two weeks ago. It also might not be his birthday at all, and they both just happen to appreciate the taste of sprinkles. We were just interpreting the facts through the lens of our birthday theory.
To be continued. We’ll discuss the keywords next time, but below are a couple of articles that I found to be well-written and helpful in explaining the differences between laws, theories, interpretations, facts, and hypotheses. I also welcome comments - did you find this helpful? Confusing? Useful? Let me know!
Bradford, A. (March 17, 2015 10:14pm ET). What is a Scientific Theory? Retrieved from http://www.livescience.com/21491-what-is-a-scientific-theory-definition-of-theory.html. Accessed February 13, 2016.
Bradford, A. (March 25, 2015 11:56pm ET). What is a Law in Science? Retrieved from http://www.livescience.com/21457-what-is-a-law-in-science-definition-of-scientific-law.html. Accessed February 13, 2016.
