## 16 Apr 2018

### Priest (11.1) An Introduction to Non-Classical Logic, ‘Introduction [to ch.11, “Fuzzy Logics”],’ summary

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[The following is summary of Priest’s text, which is already written with maximum efficiency. Bracketed commentary and boldface are my own, unless otherwise noted. I do not have specialized training in this field, so please trust the original text over my summarization. I apologize for my typos and other unfortunate mistakes, because I have not finished proofreading, and I also have not finished learning all the basics of these logics.]

Summary of

Graham Priest

An Introduction to Non-Classical Logic: From If to Is

Part I:

Propositional Logic

11.

Fuzzy Logics

11.1

Introduction

Brief summary:

(11.1.1) In this chapter we examine fuzzy logic, which assigns to sentences truth values of any real number between 0 and 1. (11.1.2) We will also discuss vagueness, which is one of the main philosophical motivations for fuzzy logic, and we will discuss fuzzy logic’s relation to relevant logics. (11.1.3) We also examine fuzzy conditionals, including how modus ponens fails in fuzzy logic.

Contents

11.1.1

[Fuzzy Logic’s Truth Values]

11.1.2

[Vagueness and Fuzzy Logic’s Relation to Relevant Logics]

11.1.3

[Fuzzy Conditionals]

Summary

11.1.1

[Fuzzy Logic’s Truth Values]

[In this chapter we examine fuzzy logic, which assigns to sentences truth values of any real number between 0 and 1.]

Priest in this chapter will cover fuzzy logic, which is “logic in which sentences can take as a truth value any real number between 0 and 1” (221).

[contents]

11.1.2

[Vagueness and Fuzzy Logic’s Relation to Relevant Logics]

[We will also discuss vagueness, which is one of the main philosophical motivations for fuzzy logic, and we will discuss fuzzy logic’s relation to relevant logics.]

Also in this chapter Priest will discuss one of the most prevalent philosophical motivation for fuzzy logic, namely, vagueness, and in addition to that he will examine “the connections between fuzzy logic and relevant logics” (221).

[contents]

11.1.3

[Fuzzy Conditionals]

[We also examine fuzzy conditionals, including how modus ponens fails in fuzzy logic.]

Additionally we will examine conditionals in fuzzy logic, noting how modus ponens may fail in it. Conditionals in fuzzy logic are called “fuzzy conditionals” (221).

[contents]

From:

Priest, Graham. 2008 . An Introduction to Non-Classical Logic: From If to Is, 2nd edn. Cambridge: Cambridge University.

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