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Dialetheism is the view that some statements can be both true and false simultaneously. More precisely, it is the belief that there can be a true statement whose negation is also true. Such statements are called "true contradictions", or dialetheia.

Dialetheism is not a system of formal logic; instead, it is a hypothesis that can be introduced as an axiom within pre-existing systems of formal logic. Introducing dialetheism has various consequences, depending on the theory into which it is introduced. For example, in traditional systems of logic (e.g., classical logic and intuitionistic logic), every statement becomes true if a contradiction is true; this means that such systems become trivial when dialetheism is included as an axiom. Other logical systems do not explode in this manner when contradictions are introduced; such contradiction-tolerant systems are known as paraconsistent logics.


The Jain philosophical doctrine of anekantavada — non-one-sidedness — states that [citation needed] all statements are true in some sense and false in another. Some interpret this as saying that dialetheia not only exist but are ubiquitous. Technically, however, a logical contradiction is a proposition that is true and false in the same sense; a proposition which is true in one sense and false in another does not constitute a logical contradiction. (For example, although in one sense a man cannot both be a "father" and "celibate", there is no contradiction for a man to be a spiritual father and also celibate; the sense of the word father is different here.)

The Buddhist logic system named Catuṣkoṭi similarly implies that a statement and its negation may possibly co-exist.

Graham Priest argues in Beyond the Limits of Thought that dialetheia arise at the borders of expressibility, in a number of philosophical contexts other than formal semantics.


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Hi Maia and everyone,

I'm not very familiar with Dialetheism, and was just gauging the interest—if there's enough, I plan to get in contact with Graham Priest to see if he'd be willing to come in and discuss or give an impromptu/casual lecture. The topic is very exciting and i think it can aid in the dissolution of dualistic thinking amongst humanity.



It seems that there is a lot of grounds for discussion within Dialetheism; beyond summarizing some of themes and systems of dialetheism, what is it you would like to discuss or investigate through this class?



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