Here is the transcript from my course on Critical thinking in Global Challenges from the University of Edinburgh by Professor Mayank Dutia and Dr. Celine Caquineu.
You may have heard people say “it’s just a theory”, or “that’s your theory”, in a dismissive way, as if a theory is just a guess or a supposition. This is a misunderstanding of what a theory actually is. This concept is a very important, and sometimes the most misunderstood, concept for critical thinking.
A theory is an attempt at an explanation. A theory is our best attempt to explain something in the natural world, based on our current knowledge and understanding. This is worth emphasising – a theory tries to explain what something is, or how something works, taking into account all the information that we currently know.
But we are always discovering new things, and understanding our world better and more fully. And this means therefore that a theory is not fixed and unchanging: on the contrary, a theory can continue to evolve and improve, as new information is discovered that may help make the explanation better than before.
Sometimes, there may be several different theories that try to explain a phenomenon in the natural world. This is often the case when we are dealing with complex phenomena, such as the global challenges, because the relevant information about these phenomena is incomplete, or unavailable. So, when we have several competing theories, how can we judge how good a theory is? The value and usefulness of a theory is measured at the end of the day by only one thing: how well it corresponds with reality.
First of all, a valid theory must be supported by evidence – that is, it must be based on facts that we know about the natural world. If a theory does not agree with our current understanding of the world, then the explanation that it provides cannot possibly be correct.
For example, for much of human history in many different cultures, epilepsy was explained as an attack by an evil spirit or a demon, and that was the accepted theory for the explanation of epileptic fits. But we now know from advances in biology and medicine what happens in the brain during an epileptic fit, and we are able to control epilepsy with modern medicines. The old theory no longer fits with our understanding of the world, and therefore it has to be discarded.
Secondly, a valid theory must make predictions that can be tested against reality – that is, testable predictions which can be checked and shown to be true – verified, or falsified. A prediction based on the theory is called a hypothesis.
The ultimate real test of how good a theory is, lies in the hypotheses or predictions that it can make. A good theory will make testable predictions, that will consistently be shown to be correct. The more correct predictions that are made by a theory, the more credible it is, and the more likely it is that the explanation that it offers is the correct one.
By contrast, a theory that does not make any testable predictions, a theory that cannot be tested in this way, is no use at all since it does not really help us explain anything.
What do we do when the predictions from a theory turn out to be wrong? In that case, the theory is obviously incorrect in its present form, because the explanation that it is offering does not fit with the real world. Then we have two choices – the theory must either change and evolve so that it fits better with reality, or if this is not possible then the theory must be abandoned and a new theory, a new and better explanation, has to be found.
Here then is a diagram showing the relationship between theories and testable hypotheses, and the importance of evidence in supporting or disproving the theory and its predictions. For the moment, this diagram shows how evidence can either support and verify the predictions from a theory, or lead to the change and evolution of the theory to better correspond to reality, or indeed lead to the rejection and abandonment of the theory, in favour of a new explanation.
We are often faced with different and competing explanations for things that happen to us, or around us – for example, different theories of why the global climate is changing, and is it man-made or not? It is important to understand the importance of evidence, and how we should use evidence to assess the credibility of different theories, instead of accepting them at face value.
Here is the link which explains the Introduction to Theory