What is asserted by the principle of noncontradiction

In the above formulation as the principle of non-contradiction the accent lies on language and the assertions made by it rather than on ontological or scientific questions as to the nature of actual things and events. As a principle in semantics it sets a norm for clear thinking and expression rather than expressing any law about the nature of things. The aim is to remove the self-contradictory use of terms and the concepts they express.

More explicitly, the principle of non-contradiction is broken in the following typical cases:- Case 1 Where the same term is used twice in opposite senses Eg 'The colour white is not a colour'.

This is a case of circularity of meaning or of a 'vicious circle in thought'. The tern 'colour' is used in two incompatible senses, for white cannot be both a colour and not a colour. We might assume that the intended assertion was badly expressed and would have been self-consistent in the expression "White is not a colour". Though white is often regarded as and called a colour in ordinary usage or in Goethe's theory of colour, Newton's theory requires that white is the neutral, uncoloured quality of light, the refraction of which alone produces colours.

We are not here concerned with the ontological or scientific question of what whiteness itself is, only with being consistent in the use of the term 'white'. Obviously the same term can be used in opposite senses in different expressions, such as in different chapters of a book.

This would extend the principle beyond its present formulation. From the Publisher via CrossRef no proxy journals. Configure custom resolver. Fosl - - Wiley-Blackwell. Contradiction and the Presupposition of Existence. Everett J. Nelson - - Mind 55 Venanzio Raspa - - Journal of Philosophical Research A Note on Contradiction: A Protest.

Nelson - - Philosophical Review 45 5 Tuomas Tahko - - Australasian Journal of Logic Meaning, Metaphysics, and Contradiction. Francesco Berto - - American Philosophical Quarterly 43 4 Clarendon Press. Dancy - - D. Reidel Pub. On Hegel's Doctrine of Contradiction.

Michael Wolff - - The Owl of Minerva 31 1 Simple Truth, Contradiction, and Consistency. Oxford University Press. Self-Deception and Belief Attribution. On the third point, Aristotle discusses views about perception and change that lead people to say that they reject PNC.

On the second point, Aristotle shows that those who say that they reject PNC do not really do so, or, if they do, they will be giving up intelligible discourse and action, and—one might add—they will be living in a world of mere sophistry and power. It is controversial how much of an essentialist or indeed realist view one must accept if one accepts PNC, but it is clear that PNC is essential for the project of an Aristotelian science.

Without it, Aristotle notes, beginners in philosophy who are interested in the truth would be off on a wild goose chase Metaph IV 5 b36—8. Acceptance of PNC, then, may also have ethical and political implications. Of course, Aristotle would agree that any argument in favor of PNC must beg the question.

Another approach is for dialetheists to refuse to let the Aristotelian reformulate their supposed counterexamples to PNC by adding qualifications so that these supposed counterexamples do not violate PNC after all. The Aristotelian can counter that without those qualifications the dialetheist has not said anything meaningful at all. Why is this not both true and false at the same time as the dialetheist contends? Besides dialetheists, some modern logicians, who need not be dialetheists, think that logic can be paraconsistent, i.

While Aristotle is obviously not a dialetheist, it is not clear where he stands on the issue of paraconsistency in Metaph IV. However one understands these passages, in the Prior Analytics , Aristotle does commit himself to the view that syllogistic is paraconsistent APr. II 15 64a This is an intriguing and relatively neglected text. At first sight it looks as if Aristotle is presenting a valid argument that includes contradictions as some of the premises, which would be surprising given his account of PNC in Metaphysics IV.

However, the text is even more obscure than usual. There are two basic interpretations. According to one interpretation, Aristotle does indeed include contradictions, but these are idle and play no real logical role in the argument he presents. There are difficulties with both interpretations. Aristotle starts by saying that no demonstration assumes PNC unless it concludes that x is F and not not- F. The text invites further elucidation. Aristotle, General Topics: logic Aristotle, General Topics: metaphysics contradiction dialetheism essential vs.

Three Versions of the Principle of Non-Contradiction 2. The Elenctic Method and Transcendental Arguments 4. The Role of Aristotelian Essentialism 6. The Principle of Non-Contradiction and Action 7.

The Argument from Conflicting Appearances 9. Dialetheism, Paraconsistency, and Aristotle Three Versions of the Principle of Non-Contradiction There are arguably three versions of the principle of non-contradiction to be found in Aristotle: an ontological, a doxastic and a semantic version.

The Role of Aristotelian Essentialism Aristotelian essentialism is the view that there exist what modern philosophers would treat as natural kinds, for example, human beings, horses and acanthus plants. The Principle of Non-Contradiction and Action Aristotle notes that even if the opponent fails to speak, she must still act, and if she acts in a certain way, that shows that she thinks that things in the world are one way rather than another, and that some courses of action are better than others.

The Argument from Conflicting Appearances In chapter 5, Aristotle distinguishes two types of opponent, those who claim to reject PNC for the sake of argument, and those Pre-Socratics who are genuinely perplexed. Aristotle presents the argument as follows: There are three sorts of cases of conflicting appearances: Things appear different to different members of the same species, e.

Things appear different to members of different species e. Things do not always appear the same even to the senses of the same individual Metaph IV 5 b8—9. It is not clear which appearances are true and which false Metaph IV 5 b If something is true it is not clear to us Democritus in skeptical mood, Metaph IV 5 b Everything is just as true as everything else. This is mentioned as an explanation of premiss 2 at Metaph IV 5 b10— Posterior Analytics I 11 This is an intriguing and relatively neglected text.

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Ross, W. For example, in Richard McKeon ed. The Basic Works of Aristotle. New York: Random House, Aristotelis Topica et Sophistici Elenchii. Aristotelis Analytica et Posteriora , with preface and appendix by L. Rowan, J. Chicago: H. Regnery Co. Plato Burnet, J. Burnyeat, M. The Theaetetus of Plato. Translation by M. Levett, revised by M. Burnyeat, and an introduction by M.

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Cambridge: Cambridge University Press, Burnyeat ed. Bury, R. Text and Translation. Carroll, Lewis, Rivista di Filosofia Neo-Scolastica , — Cassin, B and Narcy, M. Castagnoli, L. Chappell, Timothy D. Charles, David, Code, A. Cohen, S. Marc, Cooper, John M.

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