Check theories, not facts

Lessons from philosophy on how to change someone's mind

Photo by Wonderlane on Unsplash

After my recent post on fact checking, I've had a few questions about what we can do to convince people to change their minds, when that is important. There is no simple answer to this - humans in the real world are complex and have a lot going on - but there are some insights we can draw from the structure of knowledge and human thought.¹ If, as I argued, we "need to focus on the broader theories at play which stand or fall as a whole, rather than trying to focus on individual facts", then the obvious response is that we need to check theories, not facts. But what that involves and how to do it well is not so obvious.

Structure of Scientific Theories

Usefully, how people change their minds has had significant philosophical attention, albeit in somewhat disguised form. It happens to have been a major topic of interest for the philosophy of science through the twentieth century. The issue is that we tend to have a highly idealised view of how scientists come to decide which is the best scientific theory. That view tends to be that scientists calmly and disinterestedly weigh up the evidence and choose the best theory based on the current evidence. As thinkers started focusing more on how scientists actually behave, it became clear that this doesn't match many real world scientific communities. Instead, to quote the famous physicist Max Planck in the 1940s:

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

The most famous, and influential, explanation of the dynamics of how new scientific theories replace older ones, or the scientific community changes its mind, was advanced by Thomas Kuhn in his book The Structure of Scientific Revolutions in the early 1960s.² Kuhn argued that different scientific theories are not variations of each other but are better understood as competing paradigms. That is, they comprise entire ways of seeing the world with concepts and terms that were incommensurable (untranslatable) between different theories. Scientists, on this account, cannot rationally sit back and pick between different theories. A scientist needs some way of seeing the world but each of the theories instantiates a different way of seeing and interpreting the world. So they have to pick one of the theories to do any science. There is no neutral place from which they can choose.

Kuhn argued that you need to follow scientists’ behaviour over time to understand how theories change and get replaced. His observation was that, for dominant paradigms, a number of inconsistencies or questions emerge and accumulate where there are observations or experiments that the paradigm cannot properly explain. Eventually, a new theory or paradigm would be discovered that explained these inconsistencies, and the broader science, better. However, as it involved a whole new way of seeing the world, it often took a generational shift of scientists for the new paradigm to become the standard scientific understanding.

Importantly, all the scientific judgements about whether a theory or paradigm works better as a scientific theory or explanation have to take place from 'within' the theory or paradigm. Different paradigms see and explain the world differently and it is where a paradigm fails according to its own logic that it gets replaced.

How to theory-check

While there are a range of important criticisms of Kuhn's work,³ the core dynamic is important to understand as it is common to all human knowledge. Any theory, picture or paradigm that we count as knowledge exists to help us explain, make sense of and live in the world. A good theory is one that explains the world well and we can rely on. However, as we use the theory to interpret the world, we can only judge whether it is a good explanation from within the paradigm of the theory. It is when it fails to do this well - when it is inconsistent with experience or observations - that we feel the need to replace it with something better.

In other words, our theories (and so what we think we know) aren't just sets of statements we might agree to, but they fundamentally shape how we see and interpret the world. To pick up the example used in the post on fact-checking, if we think we have a responsible government we will act and interpret information very differently than if we are convinced our government is corrupt. It is only when we see what we expect to be a responsible government acting out of very different interests (or vice versa) that we change our mind. So long as we can interpret what we are seeing as consistent with our theory, there is no reason why we would abandon the theory.

That is, it is only when our expectations or explanations of the world, according to our theory, start failing against what we observe that we might start changing our mind. Our tests for whether we think a theory are true are often decided by the theory itself.

While this explains why fact-checking so often fails, it also shows how we can think about doing theory-checking instead. As there is no neutral place from the outside, the starting point has to be understanding what someone's theory itself says about how the world works and therefore what it predicts will happen. Once we have that, we can then start looking for evidence in the world as to whether these explanations or predictions are correct.

So, for example, if we want to check our theories as to whether a particular government is responsible or corrupt, we need to, at least, think through how the government would act if either of these theories is correct. If we want to convince someone else, then it would be even better to get them to articulate, in their own words, how they expect the government to act. It is only once we have these explanations and predictions that we can then move into full theory-checking mode - we can gather evidence or observe what happens to see which theory gets it right.

There are a few practical observations that are worth noting. One is that the evidence is often inconclusive, especially to force a decision between two theories. Both theories may explain the evidence, according to their own interpretations, similarly well. The second is that, as many have observed in the scientific community, one case - whether an experiment, prediction or observation - that runs counter to a theory is rarely enough to change anyone's mind. It is when, over time, a particular theory repeatedly fails then the weight of evidence builds up and it becomes harder and harder to hold.

The way this approach works in practice may be easier to see in a more personal situation. Imagine you are trying to convince a friend that a colleague of theirs isn't actually trustworthy. This is often hard to do as your friend’s paradigm is that their colleague can be trusted and so they interpret everything through that lens. Providing lots of examples of poor behaviour from the friend tends not to change anything as it mirrors a fact-checking approach.

Instead, theory-checking says you should get your friend to explain how they expect their colleague to behave in certain situations - and then see what actually happens. If they are wrong once, however, you can expect your friend to explain the situation away. But if there are ongoing and repeated times when their expectations are wrong, then they will be far more likely to accept their paradigm that the colleague is trustworthy is false.

The lesson from philosophy is that amassing facts and evidence rarely convinces people because it doesn’t reflect the structure of human knowledge and thought. Instead, we need to start from within someone's theory, beliefs or worldview and test those explanations and predictions against real world evidence.⁴ This gives us the only real test of a theory, and the one that carries the most weight with people. If it is a flawed theory, over time there will be an increasing number of discrepancies that will - logically - call into question the initial theory. At that point, if there is a viable alternative (and some other psychological factors are satisfied), the theory-checking will be successful and people may change their mind.

1. There are many psychological and social factors at play around whether and when someone changes their mind. This post is focused on the philosophy - the structure of human knowledge - and so will not be addressing any of these.

2. What follows is a high level summary of some of the core ideas.

3. For one, his insistence that different theories are incommensurable is rightly criticised as inconsistent with our observations of scientific practice.

4. There is one extra comment to make here. What different people count as ‘real world evidence’ often varies based on their theories or worldviews. Peer reviewed academic literature, to pick one example, is only seen as reliable evidence by some people in some situations.