I know the question has already been shortly answered on this website. But, I want to specifically know if Tarski's definition of truth is circular or valid? And if there is any convincingly non-circular definition out there.

It seems obviously circular to me, but it has been pointed out to me that it being circular is not the mainstream view.

We wish to prove the truth of a sentence in the object language (L), but we use a metalanguage (M) to do so, the definition is based around terms used in the sentence of L, but without the notion of "truth".

The whole thing seems circular. I mean not the definition of truth alone, but the usage of the words in the object language and the metalanguage, and the definition of truth taken together. Because, now the words in L are dependent on truth, and truth is now dependent on the same words M.

There is another issue which @Not_here has pointed out. The infinite regression between the meta languages on which to define the notion of truth on.

  • @Not_Here: Thanks, I am reading it up currently, as much as I can.
    – novice
    Nov 6, 2017 at 5:14
  • @Not_Here : That is a major issue as well. The recursion need end somewhere.
    – novice
    Nov 6, 2017 at 5:21
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    With that I'll move this to chat.
    – Not_Here
    Nov 6, 2017 at 7:00
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    The way 'truth' is defined in Western philosophy is highly arguable, to the point where it seems best to start from scratch. For me call something a truth would require that I know it is true and, as Aristotle notes, this would only be possible where knowledge is identical with its object. Ideas like 'justified true belief' make no sense on my home planet.
    – user20253
    Nov 6, 2017 at 14:55
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    @PeterJ Aristotle essentially subscribed to justified true belief:"Aletheia, truth, is rather straightforwardly recognized as applicable to mental activity in Aristotle; and specifically, the sorts of mental activity that create links of representation with existing states of affairs in the world." What you allude to is closer to Aquinas, but even in him (ideal) knowledge is identical not with the object in the usual sense, but with its form in Creator's mind.
    – Conifold
    Nov 6, 2017 at 21:10

1 Answer 1


If one must rely on Logic or Math to explain the concept of Truth, then it would be a disaster even worse than accepting there's no authentic truths at all. Fortunately C.S.Peirce has a very intuitive notion:"The opinion which is fated to be ultimately agreed to by all who investigate, is what we mean by the truth..." (http://www.peirce.org/writings/p119.html). Despite the simplicity of the statement, its meaning is profound and can be generalized to as large as science. There has been no standing still science but one to refute(falsify) others insofar as the investigating community has consensus. They always say about corroboration but that's no more than a method to reach consensus - while the results, by definition, could be as short lived as always.

Circularity is only seen when one tries to explore the absolute truth of everything and so must resort to Logic or Math. Goedle's incompleteness theorem put a barrier in trying to reach such an ideal stage. You have to switch to theology for sure if you willfully must go to the end.

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