1.6 What is a Theory?

What is a Theory?

Science operates according to the scientific method, which includes the creation of a theory or hypothesis, and the analysis and evaluation of those theories. In this section, some definitions of “theory” are explored.

The common definition of “theory” is a speculation, assumption, or conjecture. In other words, the way we commonly use the word “theory” is synonymous with "guess."

However, from a scientific point of view, “theory” is defined differently. A formal definition is: “a systematically organized body of knowledge, especially a system of assumptions, accepted principles, and rules of procedure devised to analyze, predict, or otherwise explain the nature or behavior of a specified set of phenomena.” In other words, a scientific theory is a model or framework of understanding which is used to explain something. It may include some guesswork or assumption in explaining unknown characteristics, but it’s not simply speculation without evidence.

One characteristic of a scientific theory is that it should be “falsifiable” – able to be demonstrated whether the hypothesis is true or false. This refers to the experiment and evaluation portion of the scientific method. Scientific theories go where the evidence leads. The rejection or revision of the hypothesis based on evidence should always be considered a possible outcome. If a scientist is unwilling to fairly evaluate the evidence and conclude that his hypothesis might be wrong, he will inevitably have to bend or ignore facts which disagree with his hypothesis.

This is an extremely important point to observe. A proposed explanation for which the final conclusion is held to be true no matter what the evidence shows, is not a scientific theory. Instead, this is a “tautology” – something which is asserted to be true by definition or repetition. This could apply equally to theories of creation as well as evolution.

Often the “Theory of Evolution” is derided by creationists as being “only a theory.” The intent of such statements is to caricature the scientific model (theory) of evolution using the common, non-scientific definition of theory. What they mean is, “evolution is merely an unproven conjecture.” And after all, it would be foolish to believe something that is mere conjecture, right? This method of downplaying evolution is typically employed in a scoffing tone for rhetorical value, but it is a logical fallacy of equivocation -- using two different definitions that are inconsistent.

The scientific theory of evolution is also criticized as being a tautology – something that scientists believe because they are predisposed to believing it, even though the evidence doesn’t support it. However, these are unfair and untrue characterizations. The theory of evolution is a genuine scientific theory, based on reasoned hypotheses about real evidence obtained from the physical world using a variety of scientific disciplines. It may be that the theory of evolution, or parts of it, or some of its proposed mechanisms, can be disproved based on the evidence. But to mischaracterize it using emotion-laden, non-scientific definitions, without fair consideration to the scientific issues and evidences involved, will not serve our purpose of constructing a solid Christian answer to the “evolution question.”

Further, it can be shown that, more often than not, many creationist “theories” are in fact mere conjecture, because they lack any scientific validation for their claims, and in many cases actually contradict the available evidence. Creationists who disparage evolution because it is “mere speculation” (as they claim), and yet fabricate their own highly speculative theories which they are unwilling to reconsider based on the evidence, are being dishonest and inconsistent. They are doing the very things they accuse the evolutionists of doing.

A good scientific theory is functional, in that it explains how things work, usually in terms of a prediction of how things will be expected to work in the future, or it anticipates the discovery of new evidence or principles. The theory of gravity is well understood, and can be used to explain why a ball tossed in the air travels in a parabolic trajectory. In fact, it has been demonstrated so completely and accurately as to be called the “law of gravity”; yet, we don't yet know for sure what is the actual mechanism of what causes gravity.
Even if our present theory of gravity were to be replaced in the future with better formulas or theories, they would still have to account for the evidence that is already known. In physics, this happened when Einstein's theories replaced Newtonian physics by showing that Newton's theories were special cases of more general principles. In the same way, the present theories of how biological species have developed over time will certainly be modified with further research, but any scientific theory or model (including creation theories) which claims to answer such questions must deal with and explain the existing body of real, physical evidence that is known to exist.