How Belief Works is an ongoing series of articles on the psychology of belief that's best read in sequence.

The formation of belief X is by definition due to us assessing that claim X is true – however brief, irrational, emotional, credulous or intuitive our assessment was. This answer to the question of how beliefs form can seem irrefutable, but also to be an unhelpful truism that merely raises the question of how we come to assess that X is true.

However, this apparent truism is actually false, because it's fatally logically flawed. To see why, consider first the claim Claim X is true.

The claim Claim X is true

Compare these two sentences:

1. 1. It’s raining.

   2. The claim It’s raining is true.

2 can seem to be just a different, wordier, wording of 1. That is, 1 and 2 can seem to be making the same claim. But 1 and 2 are actually making distinct claims that merely imply each other. That is, if it’s raining then the claim It’s raining is a true claim, and vice versa.

If two sentences are merely different wordings of the same claim, then, by definition, their content is the same. And if the content of two sentences is the same, then, by definition, neither sentence will refer to something that the other doesn’t refer to. But whereas 2 refers to the claim It’s raining, 1 doesn’t. That is, 1 makes, rather than refers to, the claim It's raining. 1 is about simply the current weather, rather than a claim about the current weather. Also, 2, unlike 1, refers to the concept of truth, and thereby also, unlike 1, to the relationship between the claim It’s raining and reality.

So 1 and 2 are each merely implicitly making the claim that the other is making. They can seem to be just different wordings of the same claim because the claim made by each follows so obviously from the claim made by the other that we can fail to notice the very basic logical step separating these claims.

The following two sentences are two alternative wordings of 2:

It’s true that it’s raining.

The truth is that it’s raining.

Given that they don't use the wording 'the claim It's raining' they might seem to be referring to simply the current weather, rather than to a claim about the current weather, and so to actually be different wordings of 1.

However, unlike 1, but like 2, they refer to the concept of truth. And this concept concerns a claim – specifically, the relationship between a claim and reality. By definition, a claim is a true claim – is the truth – if, and only if, it matches reality.

So when we say ‘It’s true that…’ or ‘The truth is that…’ we’re saying that the claim made by the subsequent words is a true claim. Therefore the above two sentences are actually both referring to the claim that it’s raining. That is, they’re both asserting that the claim It’s raining is a true claim, as 2 does, even though they don’t explicitly refer to the claim It’s raining as a claim, as 2 does.

The difference between the claims made by 1 and 2 of course applies to any claim, X, and the claim X is true. So claim X isn’t in itself the claim that X is true, and vice versa. Instead, each claim merely implies the other.

Now compare belief of the claims X and X is true.

Belief X versus the belief X is true

Given that the claims made by sentences 1 and 2 are different claims that imply each other, our belief of them are by definition different beliefs that imply each other. That is, if we believe that it’s raining then we’d conclude that the claim It’s raining is a true claim. And, conversely, if we believe that the claim It’s raining is a true claim then we also believe that it’s raining.

But our belief of these two claims can seem to be the same belief because, again, the claims follow so obviously from each other that we can fail to notice the very basic logical step separating them and so think that they're the same claim.

The difference between our belief of these two claims of course applies to our belief of any claim, X, and the claim X is true. So believing X isn’t in itself believing that X is true, and vice versa. Instead, believing X merely implies that we’d conclude that X is true, and believing that X is true merely implies that we believe X.

The true relationship between assessing that claim X is true and believing X

The difference between believing claim X and believing X is true implies a fatal logical flaw in the idea that the formation of belief X is due to us assessing that X is true. If the formation of belief X was dependent on us believing that X is true, then the formation of our belief that X is true would in turn be dependent on us believing that the claim X is true is true, and so on – which implies an infinite chain of belief formation. So belief formation would be impossible.

And there’s actually a second fatal logical flaw in this theory of belief formation – one which reveals the true relationship between assessing that X is true and believing X.

Again, by definition, a claim is a true claim if, and only if, it matches reality. So the only way to assess whether a claim is a true claim is to assess whether it matches reality. And the only way to assess whether a claim matches reality is to compare it with reality. But, logically, when we compare a claim with reality we can only ever compare it with what we believe about the relevant aspect of reality at the moment of the comparison, even when the comparison uses the current content of our senses.

So our assessment that the claim It’s raining is a true claim must be based on our belief that it’s raining. That is, this assessment must be preceded by our belief that it’s raining. So the formation of our belief that it’s raining can’t ever be due to us assessing that the claim It’s raining is a true claim.

And this logic of course applies to the formation of any belief: the formation of our belief of claim X can’t ever be due to us assessing that X is true, because that assessment is always based on, and so preceded by, our belief of X.

Although, the process of assessing the truth of X can lead to the formation of belief X, because this belief may only form during that process, the moment before we conclude that X is true.

Note also that although our assessment that X is true is by definition an instance of belief formation that's due to an assessment of truth, this belief involves the claim X is true and yet is due to our assessment that X, not X is true, is true.

Potential objections

Objection 1

It might be objected that even if we accept the above analysis there’s still one scenario in which formation of belief X is due to us assessing that claim X is true.

If we read or hear X, and we neither believed or disbelieved X immediately before doing so, and we completely trust X’s source on the subject of X, then we can assess that X is a true claim based on that trust, and this assessment will then immediately lead us to conclude X. This sequence of events doesn’t imply the infinite chain of belief formation that I referred to earlier, given that our belief that X is true is based on our trust of X’s source and so isn’t dependent on us believing that the claim X is true is true.

Of course, not all of our beliefs form via us reading or hearing the believed claim. Indeed, in the above sequence of events our belief that X is true forms via our trust of X’s source rather than via us reading or hearing the claim X is true. So the aim of this objection isn’t to show that the formation of belief X is always due to us assessing that X is true. Indeed, if it was, the objection wouldn’t provide a solution to the resulting problem of the infinite chain of belief formation.

But the objection doesn’t even succeed in its limited aim of showing that the formation of belief X is sometimes due to us assessing that X is true, because it has two flaws.

First, in the above sequence of events our conclusion that X is a true claim actually isn’t an assessment that X is a true claim.

Again, by definition, a claim is a true claim if, and only if, it matches reality. So the only way to genuinely assess whether a claim is a true claim is to assess whether it matches reality. And the only way to genuinely assess whether a claim matches reality is to compare it with reality – that is, compare it with what we believe about the relevant aspect of reality at the moment of the comparison, even if that belief is based on the current content of our senses.

So if our conclusion that a claim is a true claim is based on simply a consideration of its source, and therefore not on a comparison of it with reality, then it’s based on an assessment of not its truth but that source. Therefore in the above sequence of events the formation of belief X is actually due to us concluding, but not assessing, that X is true.

The second flaw in this objection is that our complete trust of X’s source on the subject of X actually leads directly to us concluding X, rather than via concluding that X is a true claim.

That is, although that complete trust means, by definition, that we believe that all claims produced by the source on the subject of X can be believed to be true claims, this in turn means that we also believe that all such claims can be believed. So upon reading or hearing X we can conclude X directly rather than via concluding that X is a true claim. And given that the former cognitive route to concluding X is shorter than the latter, we conclude X via the former route before we’ve had a chance to do so via the latter.

Objection 2

It might also be objected that if our assessment that claim X is true was based on our belief of X, rather than the reverse, then our belief of X would lead us to always assess that X is true and that any contrary claim is false, and so we’d never change our belief, and yet we do change our beliefs.

But this objection wrongly assumes that if we believe X then changing this belief is dependent on us assessing that X is a false claim and that a contrary claim is a true claim. Just as the formation of belief X can't be due to us assessing that X is a true claim, because that assessment is based on that belief, so the subsequent formation of a contrary belief, and thus the end of our belief of X, can’t be due to us assessing that the contrary claim is a true claim and that X is a false claim, because the reverse will be true.

Also, as I said earlier, the process of assessing the truth of X can lead to the formation of belief X, because this belief may only form during that process. Likewise, if we believe X and then assess the truth of both X and a contrary claim, we can change to believing the contrary claim during this process, and then assess that the contrary claim is a true claim and that X is a false claim. So believing X before assessing the truth of both X and a contrary claim doesn’t even mean that we’ll necessarily assess that X is a true claim and that the contrary claim is therefore false.

The origin of this false theory of belief formation

The origin of the idea that the formation of belief X is due to us assessing that claim X is true is likely due to the combination of the following factors:

• Belief of the claims X and X is true can seem to be the same belief.

• If our belief of X only formed during the process of assessing the truth of X, then that process was a critical part of the cognitive chain of events that led to our belief of X. And this can lead us to wrongly think that the formation of belief X was due to us assessing that X is true – especially given that our belief of X will have formed only the moment before we concluded that X is true.

• When we compare claim X with reality, in order to assess the truth of X, we can easily forget that, logically, we can only ever compare X with what we believe about the relevant aspect of reality at the moment of the comparison, even when the comparison uses the current content of our senses. So when we assess that X is true we can wrongly think that we compared X with reality itself, rather than merely our belief about the relevant aspect of reality, and so only formed our belief of X upon forming that assessment.

• When we conclude that X is true based on our complete trust of X’s source on the subject of X we can wrongly think both that this conclusion is an assessment of truth and that it led to the formation of our belief of X.

So why do we believe what we believe?

There’s actually a third fatal logical flaw in the idea that the formation of belief X is due to us assessing that claim X is true.

We obviously can only begin to assess the truth of a claim after it has entered our mind. But concluding X involves X entering our mind upon it being generated by our reason, and a conclusion is by definition a belief. So we can believe X before we’ve had a chance to even begin to assess the truth of X.

The fact that a conclusion is by definition a belief can also seem to provide the answer to the question of how beliefs form. The formation of belief X is due to us concluding claim X – however brief, irrational, emotional, credulous or intuitive our reasoning was. Again, when we read or hear X we can then conclude X based on simply our complete trust of X’s source on the subject of X.

It might be thought that the formation of a belief about our surroundings or body via sensory perception doesn't require reason. For example, it might be thought that to see rain is in itself to believe that it's raining. But even such belief formation requires reason.

Belief involves a claim, and the formation of any belief involves thinking the claim concerned. So the formation of a belief about our surroundings or body via sensory perception involves the generation of a claim about the physical world, and us thinking that claim. For example, the formation, via visual perception, of our belief that it's raining involves the generation of the claim It's raining, and us thinking 'It's raining'.

And yet the output of a perceptual process is in itself simply a perceptual experience of the physical world. In the example, the output of the visual process is in itself simply our visual experience of rain. That is, the output of a perceptual process is the content of one of our senses, not a thought about that content.

When we form belief X about our surroundings or body via sensory perception claim X is generated by our reason based on our perceptual experience, with our thinking X being the output of that reasoning. But such reasoning is often so basic and therefore brief that the resulting belief can seem to be a direct product of the perceptual process.

Note that the term perception can be used to refer to an understanding – as in, for example, Different people can have different perceptions of what constitutes living morally. And a perception in this sense is by definition a thought. But this is a different sense of this term from sensory perception.

The theory that the formation of belief X is due to us concluding X can seem true by definition and therefore irrefutable. But so can the theory that the formation of belief X is due to us assessing that X is true. And, incredibly, even the former is fatally logically flawed – as I'll show in the next article.

Next article: How Beliefs Form – Part 2

How Belief Works