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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.

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  • [Burke 1994] Burke M. B. (1994). Denying the antecedent: A common fallacy? Informal Logic 16 pp. 23-30.

  • [Floridi 2009] Floridi L. (2009). Logical fallacies as informational shortcuts. Synthese 167(2) pp. 317-325.

  • [Fox and Das 2000] Fox J. and Das S. (2000). Safe and Sound: Artificial Intelligence in Hazardous Applications. Menlo Park CA: MIT Press.

  • [Godden and Walton 2004] Godden D. M. and Walton D. (2004). Denying the Antecedent as a Legitimate Argumentative Strategy: A Dialectical Model. Informal Logic 24(3) pp. 219-243.

  • [Groarke 2011] Groarke L. (2011). Informal Logic. Stanford Encyclopedia of Philosophy

  • [Layman 2002] Layman C. S. (1999). The Power of Logic. The McGraw-Hill Companies Boston.

  • [Moldovan 2009] Moldovan A. (2009). Pragmatic Considerations in the Interpretation of Denying the Antecedent. Informal Logic 29(3) pp. 309-326.

  • [Orsinger 2011] Orsinger R. R. (2011). The Role of Reasoning in Constructing a Persuasive Argument.

  • [Stone 2012] Stone M. (2012). Denying the Antecedent: Its Effective Use in Argumentation. Informal Logic 32(3) pp. 327-356

  • [Walton 2002] Walton D. N. (2002). Are Some Modus Ponens Arguments Deductively Invalid? Informal Logic 22(1) pp. 219-243

  • [Yaskorska et al. 2012] Yaskorska O. Kacprzak M. & Budzynska K. (2012) Rules for Formal and Natural Dialogues in Agent Communication. In Proceedings of the international workshop on concurrency specification and programming pp. 416-427. Berlin: Humboldt-Universitat zu Berlin 267

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