I am just wondering if a specific fallacy applies to this kind of situation.

A experiences an event X, which we later note seems correlated with Y - but not causally.

Upon telling A that X correlates with Y, there is the possibility that A will experience more strongly X when Y occurs, though it is not necessarily causal.

Would this be cum hoc ergo propter hoc, a self-fulfilling prophecy, or a bit of both?


  • Might be an example of confirmation bias. Commented Nov 7, 2019 at 7:56

4 Answers 4


It's not clear that this would be fallacy for the simple fact that there does not seem to be any kind of thinking, reasoning, or argumentation going on in the first place. Rather, you seem to be describing some kind of psychological change that is happening to $A$ ... though frankly I am not even clear what exactly that psychological effect is, because you say:

A will experience more strongly X when Y occurs

What does that even mean? What does it mean to "experience more strongly" some event?

  • That looks like a comment to me.
    – Joachim
    Commented Nov 6, 2019 at 21:45

Bram28 is right in noticing that this is not a matter of argumentation. Generally, when people experience an irrational change in "experience", as per your statement:

there is the possibility that A will experience [emphasis mine] more strongly X when Y occurs, though it is not necessarily causal.

what is happening is known as a cognitive bias, which may or may not result in a logical fallacy. For instance, even though a person might experience what you mention, namely, illusory correlation, that same person might identify their own cogntive distortion and find the correct form of reasoning. This, after all, is a largely accepted pursuit of both philosophy and contemporaneously, talk therapy. The difference between bias and fallacy is largely that bias refers to how the brain works in psychological context, and fallacy refers how to logic works in the context of argumentation.

Here's a WP list of cognitive biases for perusal. Here's a WP list of logical fallacies.


The thinking/reasoning was pertaining to the construction of a psychological experiment, yes.

In a lab setting, it was noticed that subjects experience X during Y. It was suggested to inform the subjects that this is a correlated event, but the suggestion was rejected because it was thought that by being made aware of this potential relationship, the subjects would be more likely to report instances of X during Y, simply by virtue of knowing about the potential relationship.

Perhaps my wording "experience more strongly" was a poor choice; or perhaps it does not involve thinking/reasoning, as you say.

Consider "more likely to experience," though that may be equally ambiguous.

A notes X happens during Y. A finds a correlation of this fact. A then goes on to report more instances of X during Y simply because they are aware of the possibility that X occurs during Y.

I thought it might have been similar to the Historical Fallacy, or cum hoc ergo propter hoc, as I stated in the original question. Though I suppose I am mistaken.

  • Why do you use another account to comment on and answer your own question?
    – Joachim
    Commented Nov 6, 2019 at 21:46

Perhaps you have in mind the following possibility. There is no indication from the example that A has noticed X, Y or any relationship between them. But when alerted to the fact that there a correlation between X and Y, when Y occurs the possibility or probability that X has occurred or will occur acquires an interest or importance or just plain curiousity about X that A had not had before.

This is a genuine possibility and it can occur without the Y/X correlation's being (or even being supposed to be) causal. All this can be so but I think the matter belongs to psychology - 'folk' or scientific - rather than to philosophy. It is not the philosophy but the psychology of perception that is involved here. Or so it seems to me but I am open to correction.

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