<abstract xmlns="http://www.w3.org/1999/xhtml"><p> The precedent studies on the validity of Modus ponens and Modus tollens have been carried out with most regard to a major type of conditionals in which the conditional clause is a sufficient condition for the main clause. But we sometimes, in natural language arguments, find other types of conditionals in which the conditional clause is a necessary or necessary and sufficient condition for the main clause. In this paper I reappraise, on the basis of new definitions of Modus ponens and Modus tollens, their validity/invalidity in natural language arguments in consideration of all types of conditionals.</p></abstract>

The precedent studies on the validity of Modus ponens and Modus tollens have been carried out with most regard to a major type of conditionals in which the conditional clause is a sufficient condition for the main clause. But we sometimes, in natural language arguments, find other types of conditionals in which the conditional clause is a necessary or necessary and sufficient condition for the main clause. In this paper I reappraise, on the basis of new definitions of Modus ponens and Modus tollens, their validity/invalidity in natural language arguments in consideration of all types of conditionals.

MODUS PONENS AND MODUS TOLLENS: THEIR VALIDITY/INVALIDITY IN NATURAL LANGUAGE ARGUMENTS

Studies in Logic, Grammar and Rhetoric

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

The precedent studies on the validity of Modus ponens and Modus tollens have been carried out with most regard to a major type of conditionals in which the...

MODUS PONENS AND MODUS TOLLENS: THEIR VALIDITY/INVALIDITY IN NATURAL LANGUAGE ARGUMENTS

Published Online: Oct 31, 2017

Page range: 253 - 267

DOI: https://doi.org/10.1515/slgr-2017-0028

Keywords
affirming the antecedent, affirming the consequent, argumentation, denying the antecedent, denying the consequent, modus ponens, modus tollens, validity

© Studies in Logic, Grammar and Rhetoric

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

MODUS PONENS AND MODUS TOLLENS: THEIR VALIDITY/INVALIDITY IN NATURAL LANGUAGE ARGUMENTS

Published Online: Oct 31, 2017

Page range: 253 - 267

DOI: https://doi.org/10.1515/slgr-2017-0028

Keywordsaffirming the antecedent, affirming the consequent, argumentation, denying the antecedent, denying the consequent, modus ponens, modus tollens, validity

© Studies in Logic, Grammar and Rhetoric

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
affirming the antecedent, affirming the consequent, argumentation, denying the antecedent, denying the consequent, modus ponens, modus tollens, validity