Present discourse is replete with rogue actors. People publish and promote statements with no evidence or grounds, but the simple act of saying them seems to introduce the possibility of their truth into the epistemic considerations of the listener. If a listener judges that there is a very small but non-zero probability that what is being claimed could be true, then the model of possible worlds being considered by the listener seems to have been expanded to include those claims, with only unreliable testimony as the support for that expansion.

While it would seem as though independently the listener deems that what is being claimed is unlikely, in the possible world where the statement were true, then this testimony would seem to support it. Given that it was in fact unlikely but true, and our testifier stated it correctly, it seems as though one’s estimation of the testifier’s reliability should be revised upwards in that situation, and their testimony as included among items of supporting evidence for believing the claim.

There’s a kind of “boy who cried wolf” principle at work here. The boy (who I'd mistakenly named Peter before) spoke truthfully the third time, but by then his epistemic credibility had been blown. Someone who took [Peter]’s third claim seriously would be in a much stronger position relative to the facts in the case where the wolf really was coming, and trust in [Peter] would be to some extent restored, but there is a sense in which this act of epistemic trust would be ill-founded - if there had been no wolf the third time, we are inclined to say the belief was groundless in the first place.

But was it? Are there accounts of testimony that say that even unreliable, false testimony provide support for the beliefs about the reported propositions? And if so, how do those models tackle wilful disinformation?

  • 1
    Just saying: You are confusing the story of “Peter and the Wolf”, where Peter is the hero catching the dangerous wolf, with the fable of “The boy who cried wolf”.
    – gnasher729
    Jul 29, 2023 at 16:56
  • Ah, quite right! (and no, this is a genuine mistake, not a deliberate meta-irony!) I'll make the amendment.
    – Paul Ross
    Jul 29, 2023 at 17:00

1 Answer 1


Well, in a world increasingly awash with information, the challenge is to discern truth from falsehood. The issue you've described, where false or unreliable testimony expands the realm of possible truths, is a real concern. It's the reason why we have to be extremely careful about our sources of information and vigilant against disinformation.

Unreliable testimony, even when it occasionally aligns with truth, doesn't fundamentally support a belief system grounded in truth. Instead, it fosters an environment of confusion and mistrust. It's like navigating a ship in a storm with a faulty compass. Yes, there may be moments when the compass points in the right direction, but it's unreliable and dangerous to rely on.

The story of 'Peter and the Wolf' illustrates this perfectly. Even when Peter tells the truth the third time, the damage to his credibility from his previous false alarms means his truth isn't believed. This is a critical lesson about the long-term consequences of providing unreliable testimony.

As for the question of whether false testimony can support true beliefs, I would argue it's a risky and unstable foundation. A belief system founded on unreliable testimony might occasionally stumble upon the truth, but it's more likely to lead one astray. It's far better to seek out reliable, credible sources of information, and to foster a culture of truthfulness and authenticity.

When it comes to wilful disinformation, the challenge is even greater. We must strive to educate ourselves and others about the importance of truth and the dangers of disinformation. We must also hold those who spread disinformation accountable for their actions

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