Document Type : Research

Abstract

Different kinds of nonstandard conditionals of modal nature, are studied in conditional logic or Dyadic Modal Logic. Preference structures are one of the important categories of semantic models for these logics. Deontic conditionals and nonmonotonic conditionals are two kinds of these nonstandard conditionals, such that these models have been introduced as one of their main semantics.
In this paper we have a brief review of the literature of preference models in these two branches. Then we compare the subjects studied under the topic of preference models in both fields and have an analysis about the meaning and the acceptance of the axioms of conditional logics, when the conditionals either read as deontic conditionals or as nonmonotonic ones.
In addition, we present some examples to show that in the both fields, preference models have shortcomings in expressing the correct and intuitive reasoning. We offer some extended semantics from nonmonotonic literature to overcome these shortcomings.

Keywords

• Deontic Logic
• Nonmonotonic Logic
• Krepke Models
• Conditional Logic
• Preference Structures

Main Subjects

• Philosophical Logic