What Is a "Theory" and Why Is It Important to Know?

When asked the question, "What is a theory?" most of my students (regardless of age or educational level) respond with an explanation that is akin to "a reasonable, educated/informed guess."

Indeed, consistent with this perspective, the phrase "it’s just a theory" (be it in reference to one’s humility regarding their own standpoint or trying to denigrate another) is one I’m sure many of you have heard thrown around from time to time. The problem is that these common perspectives are not correct—which makes me wonder, is the majority of the population misinformed as to what theory refers to?

While many conceptualise a theory as a reasonable, educated guess, what they’re really describing is a hypothesis (i.e. a proposed outcome, explained on the basis of limited evidence or a thread of logic as a starting point for further investigation). A theory is more concrete than an educated guess. In order to appropriately explain the concept of theory, it’s important to first set the scene:

For centuries, it was believed that all swans are white. Then one day, a black swan (cygnus atratus) was spotted and "knowledge" had to be amended. The original perspective was falsified (e.g. see Popper, 1934/1959). More recently, knowledge once again required amendment—there are no longer nine planets, but rather eight. The more knowledge we obtain, the better our understanding becomes; and as we come to understand more, further amendments may be required to what we once thought we knew. Critical thought is cautious and accounts for amendment when necessary (e.g. see discussion on reflective judgment and "proof").

Let’s consider another example. We are familiar with the "Law of Gravity"—a crude description of its function on Earth being the acceleration of objects to the ground at 9.81 m/s². However, calling gravity a "law" is a misnomer. Gravity, as I imagine many readers will know, is actually a theory. But why?

Let’s be clear, if I’m holding a coffee bean in my hand and release it, I’m going to bet my house that the outcome will be that it falls to the ground. However, we can never be 100% certain that this event will occur; and there are numerous reasons for this. Let’s discuss two here.

First, what if our understanding of gravity is incorrect? What if there are, as of yet, unobserved characteristics of our current conceptualisation of gravity? What if there’s more to it than we think? You might say, "Surely, we would have seen such characteristics by now?" Well, the same could be said about being able to count planets. Remember, neither of these examples/potentialities is a function of being wrong about a phenomenon, rather they are a function of learning more.

Second, we cannot see into the future—we can never be entirely certain that something will happen; though we might have a strong theory as to what will happen (e.g. the coffee bean will likely fall to the ground). Our hypothesis is one of extreme confidence. Why? Well, gravity is a strong theory. But what happens if an asteroid hits the Earth tomorrow, knocks us off-axis, changes our polarity, and plays games with our planet’s electromagnetism? Perhaps "gravity" will then behave differently. Of course, this is extremely unlikely; but, there is still the possibility, no matter how minute; and as a chance exists (regardless of how minute), that means that we cannot be 100% certain of the original premise.

Again, this talk of gravity is a rather extreme analogy for my point; and in no way, shape or form do I question or will I test the force of gravity, but it does provide a good example for consideration. So, then, is a theory a law? No, simply, this example makes the point that the use of "laws," in this context, is inaccurate. So, what actually is a theory?

A theory is an established model for why or how a given phenomenon occurs—it is an explanation of observed regularities. The terms "established" and "observed regularities" are important here. Theories are developed based on observing similar outcomes over and over again. This is a fundamental reason why replication in research is so important. It is also why any one piece or even bodies of research cannot "prove" a theory true; rather replication provides further evidence to support a theory—it strengthens a theory. Returning to the example of gravity, it is such a strong theory because it has been observed time and time again without ever being falsified.

Okay, so a theory is a much stronger notion than many may have thought. It’s certainly stronger than an educated guess. But, how does that affect your day-to-day life? Well, knowing what a theory actually is will help your decision-making in terms of navigating the terrain of what research says in relation to how society and media represent it. For example, when someone you know states that "evolution is just a theory," you know that it actually means that the concept of evolution is based on a model of replicated data observed time and time again; thus making it a leading explanation for why events in that particular context occur—it’s not just some unestablished guess.

Cognition Essential Reads

5 Science-Backed Ways to Write Clearly

Explaining the NBC Theory of Consciousness

Likewise, you may have in the past said to yourself or explained to your friend that some notion is "just my theory" – unless the phenomenon has been observed regularly, over and over, you know that such a perspective is inaccurate. Notably, if it’s something that you, alone, have observed time and time again, it’s still inaccurate—your personal experience and anecdotal evidence are not sufficient grounds to develop a theory. The observation requires replication by others as well. Truly understanding what a theory is and the mechanics behind falsification are fantastic ways for individuals to begin embracing the concept of intellectual humility, through engaging in epistemological consideration regarding the nature of knowledge and the concept of "certainty."

In conclusion, a theory is much more than a hypothesis—it comes from a strong evidence base and should not be cast aside as if it were a guess. If you truly care about the topic you are thinking about, you will consider empirically-based theories. However, just because you know that a theory is an established model for why or how a given phenomenon occurs, doesn’t mean that everyone else does. Be cautious in interpreting how people throw the term around and strive for clarification.