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Logical laws

DOI: 10.4324/9780415249126-X022-1
Version: v1,  Published online: 1998
Retrieved July 07, 2020, from

Article Summary

There are at least three different kinds of answer to the question ‘What is a logical law?’ One establishes what it means for something to be a logical law. This answers the semantic question: What is the meaning of ‘logical law’? The second explains what makes something a logical law. This answers the metaphysical question: What is the ground of logical law? The third tells you what the logical laws are. This answers the question: What is the extension of ‘logical law’?

Even though logic is often seen as a complete science, the answers to all three questions are disputed. For example, there are at least three different conceptions of what it means for something to be a law of logic. Different conceptions account for logic in terms of necessity, truth in all models, and proof.

There are also different answers to the metaphysical question. If truth-preservation is central to logic, then the ground of logic depends on the metaphysics of truth. If logic is a matter of the meanings of terms, then the metaphysics of meaning is important for logic. Unfortunately, there is no widespread agreement on the metaphysics of meaning or truth.

Finally, there is no widespread agreement as to what the logical laws are. There are two general disputes here. First, it is not clear what notions count as logical. Does logic contain laws about identity, second-order quantification or modality? Second, given agreement on the scope of logic, there are still questions about the logical laws in that area. Intuitionists, quantum logicians, relevance and paraconsistent logicians each reject things taken as laws by others, even in the language of ‘and’, ‘or’ and ‘not’.

Citing this article:
Restall, Greg. Logical laws, 1998, doi:10.4324/9780415249126-X022-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2020 Routledge.

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