Sorites Paradox and the Need for Many-Valued Logics

ŠTĚPÁNEK, Jan. Sorites Paradox and the Need for Many-Valued Logics. In 5th World Congress and School on Universal Logic, 25.-30. 6. 2015, Istanbul. 2015.

Basic information

• Original name: Sorites Paradox and the Need for Many-Valued Logics
• Authors: ŠTĚPÁNEK, Jan (203 Czech Republic, guarantor, belonging to the institution).
• Edition: 5th World Congress and School on Universal Logic, 25.-30. 6. 2015, Istanbul, 2015.

Other information

• Original language: English
• Type of outcome: Presentations at conferences
• Field of Study: 60300 6.3 Philosophy, Ethics and Religion
• Country of publisher: Turkey
• Confidentiality degree: is not subject to a state or trade secret
• WWW: URL
• RIV identification code: RIV/00216224:14210/15:00083537
• Organization unit: Faculty of Arts
• Keywords (in Czech): sorites paradox; vágnost; logika; vícehodnotové logiky
• Keywords in English: sorites paradox; vagueness; logic; many-valued logic
• Tags: mzok, rivok
• Tags: International impact

Abstract

Sorites paradoxes are a class of paradoxical arguments which arise as a result of using vague terms such as "heap" or "bald". While precise terms have sharp boundaries of application, vague terms lack such precise boundaries. With vague terms there are objects to which: a) the vague term applies, b) the vague term doesn’t apply, and c) it is uncertain whether vague term applies or not (so called borderline cases). In borderline cases it is uncertain whether the vague term in question applies to them or not. Moreover, this uncertainty cannot be resolved by any enquiry. Since there are three aforementioned classes into which we can divide objects in a range of significance of any vague term, it might be tempting to use three-valued logic to deal with sorites paradoxes. This way we can ascribe exactly one truth value to all sentences of sorites paradox and we needn't resort to either supervaluationism or subvaluationism. Another approach to solving sorites paradoxes is based on an intuition that vagueness is a matter of degree and logic of vagueness should reflect that with different degrees of truth. If A measures 190 cm and B 195 cm then sentence "B is tall" seems to be truer than "A is tall". Fuzzy logic therefore takes advantage of its infinitely many truth values. In my talk I will critically assess many-valued logics and fuzzy logic. My goal is to show that these approaches to sorites paradoxes either have presuppositions that their proponents wouldn’t assent to or that they generate more problems than they claim to resolve.

Links

• MUNI/A/1153/2014, interní kód MU: Name: Soudobé problémy a minulé podoby filozofické diskuse

Investor: Masaryk University, Category A