Of theories and Theories

A fundamental instrument in the toolbox of anyone who **really** understands science is the capacity to distinguish between the term “theory” in a colloquial sense and the word “Theory” as used in science.

Many people confuse the two and this shows a fundamental misunderstanding about the scientific process. Some time ago wrote a post that tried to explain the difference between the two. I have updated the relevant section and I have reprinted it below. If you want to see the complete post you can find it here.

Evolution: of theories and Theories

Evolution is often dismissed as a mere “theory”; well, it is a theory, or rather, it is a Theory. Confused? You are not alone. The confusion is brought about by the usual lack of a clear distinction in most people between two of the meanings of the word. A “theory” (uncapitalized) is essentially a guess, an opinion, as in “ . . . this is how I think it happened . . .”. As written, if you want to confirm it or dismiss it, you must find evidence to support (or not support) your interpretation of the events.

A “Theory” (capitalized) in the scientific sense is a model that collects a wide variety of phenomena and integrates them in a coherent framework independently of personal opinions. In this way, a Theory will be capable of explaining additional observations and most importantly, make predictions. The additional observations are used to modify the Theory and in some cases, even change it altogether.

A very dangerous consequence of the sometimes deep misunderstanding of scientific principles is that people confuse “facts” with “Theories”, even people who should know better. There’s no shame in that, even seasoned scientists fall into that trap. Scientists are human, and are capable of really bad lapses in judgement… But. I (as usually) digress.

Back to topic, for example, things fall towards the ground. This is an undisputed fact that can be verified by everyone. We (humans) have described this as “gravity”, and we can come up with many different explanations of why it happens. In fact, since antiquity, there have been several explanations to account for the fact of gravity, all the way up to Newton and Einstein, yet the proverbial apple does not care about the mechanism; it falls to the ground regardless.

Therefore, even though we have a current Theory of gravitation, we do not think of gravity as something dependent on our personal opinions. Gravity happens, whether you like it or not.  In this sense, gravitation is both a fact and a Theory.

The same reasoning can be applied to evolution. The undeniable fact is that life on our planet has changed over time. This has been thoroughly documented by many lines of evidence.

This is a fact. Pure and simple. No “buts” or “maybes”.

A vast collection of Theories of evolution, on the other hand, have historically tried to explain this change of biological life over time through a variety of different mechanisms. The best available evidence points at natural selection as the most likely mechanism that accounts for evolutionary change. More recently, some scientists have suggested symbiosis (the close interaction of organisms belonging to different species) as a source for evolutionary innovation. The nature of science, particularly biology, is rarely black or white; there are many shades of gray.

For the record, I think that the right answer to account for evolutionary change might just be a combination of natural selection and symbiosis, but this is beside the point. It is just an opinion, as I am not a qualified evolutionary biologist.

The important thing is that whether symbiosis, natural selection, a combination of the two, or even a yet undiscovered mechanism explains evolution the best (and trust me, scientists have argued and will keep arguing about this), ***has no bearing on the fact of evolution***. Life happened, and has changed over time, period.

For a more thorough (and much better written) exploration of evolution as fact and theory see


Another source of confusion is when somebody finds to his utter surprise that science is not written in stone, in other words, that science is provisional.

Science is provisional indeed, but some things are more provisional than others. The amount of evidence in favor of a certain interpretation of nature is inversely proportional to how provisional that interpretation is. In other words, the more evidence for something, the less provisional character it has.

It is a fatal mistake to think that in science all “provisionals” are equivalent.

A final thought in this topic. At the present level of our understanding of the universe, we cannot try to understand it from the proverbial engineering point of view. We are not that smart yet. If only the universe’s reality were that simple! To think that at the present we can always describe the natural world in terms of A goes to B then to C, etc.

To treat all “provisionals” as equals is a gross oversimplification of the nature of things and at the same time a hilarious overestimation of our true capacities.

If you want to know more:


***WARNING: ANY AND ALL UNSCIENTIFIC STATEMENTS ARE SUBJECT TO PAGANIZATION (Oh, you do not know what this procedure is? Please click here)




  1. No where is this failing of our understanding more obnoxious than in the anti-evolution movement. As Richard Dawkins said:

    “It is absolutely safe to say that if you meet somebody who claims not to believe in evolution, that person is ignorant, stupid or insane (or wicked, but I’d rather not consider that).”

    He overstates it somewhat, but ultimately I think he’s correct. Those people who will deny the fact of evolution (or gravity or what have you), based on the mistaken idea that “it’s just a theory” are almost universally the least likely to have read anything on the subject.

    I very much like the way you’ve worded this…thank you!


    1. I agree. Terms are important! The same could be said about climate change, etc. Now about Dawkins… He has a point, but it is in my opinion, badly expressed. Maybe is a biased reaction on my part. I really dislike the “angry intellectual” ways (theist or atheist, they act the same). I will message you privately to give you a more complete perspective of what prompted me to update the post… Thanks!


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