One of the most troubling slogans in modern times is “In theory, everything is possible”. This is not true for any accepted meaning of the term ‘theory’ – at least, not if one is claiming any relationship between the content of the ‘theory’ and the actual behavior of the universe in which we live. Rather it is a sign of intellectual laziness, of being unwilling to confront the potential falsehood of an idea which is personally gratifying.
Such statements as “Truth is beauty, beauty truth”, while emotionally satisfying and inspiring, do not actually tell us anything concrete about the way the universe functions. In this article, we make the tacit assumption that interesting issues concerned with fact must use reality as a touchstone.
So what is a theory, what is a fact, and what (if anything) is the difference? These are essentially philosophical questions, and as such are to some extent unanswerable. Despite this, there are commonly held positions on these questions, and we will try to present an intellectual middle ground while remaining as uncontroversial as is possible while discussing such a topic.
Let’s begin with restricting the playing field. What most people think of as a theory is actually a hypothesis – a bare idea about how the universe might behave. The difference between a hypothesis and a theory is that a theory has been tested for accuracy against the behavior of the universe.
For example, if one offers the hypothesis that aliens have visited our planet in historic times, this does not constitute a theory. If one accumulates credible evidence of such visits, then the hypothesis may form the basis of a theory. We would still need to explain (and prove and test) the reason for the visitations to form a full theory, but the basis upon which to build a theory would then exist.
If a person says that they weigh 150 pounds (give or take a few) as measured on the surface of Earth as of a certain date, determining if this is a fact requires comparison with the external universe. Of course, this assumes that there is an external universe, but let’s not go there at this time.
Given that our ultimate criterion for philosophical concepts is comparison with a ‘real’ external universe, what are theories and facts? Perhaps the best place to start is with a reasonable definition of a fact. The position taken for this article is essentially that of science.
Facts are reasonably straightforward. A fact is the state of affairs (in the external universe) as reported by a true sentence. “I weigh about 150 pounds on Earth”, unfortunately, is not a fact, as the sentence is not true. In fact, the author weighs quite a bit more than that (the details are none of your business!).
Theories are a bit more tricky. Briefly, a theory is a story that explains why and how something happens. But that definition could be applied equally to myth and fantasy. How do we differentiate? By using the universe as a touchstone for separating truth from fantasy.
Any acceptable theory will produce accurate predictions about the behavior of the universe. If the predictions of a theory agree with the behavior of the universe, it may be a valid description about how phenomena actually occur. If most of the predictions agree with how the universe behaves, the theory can be a useful guide without being ‘true’ in some sense.
An example would be Newton’s laws of motion. We know that these ‘laws’ are not ‘true’, in that they make predictions about the evolution of the universe which are not accurate. However, they are pretty close to accurate in the majority of situations we encounter in daily life. As a result, theories based on Newton’s laws, while not a totally accurate model of reality, are very useful. The real behavior of the universe is still the touchstone for truth, but even limited theories are of practical use.
Is a model that works ‘pretty well’ a theory, or a children’s story? Somewhere in between, depending on your philosophical orientation. It is certainly true that limited stories can be useful and instructive, but often the limitations teach one more about reality. Are such stories ‘true’? No, but they do reflect some measure of the truth about how the universe behaves.
The interaction between experimental or observational ‘fact’ and our ‘theories’ about how the universe behaves are perpetually interwoven in a fascinating dance. In essence, our theories predict what facts will result from observations about the universe, and are acceptable depending on the accuracy of those predictions. A great deal of evidence is required to establish a good theory – the term should not be cheapened in the attempt to promote an unsupportable intellectual position.