<!DOCTYPE html><HTML lang="en"> <head><meta charset="utf-8"> <title>Lewis (David) - Counterpart Theory and Quantified Modal Logic (Theo Todman's Book Collection - Paper Abstracts) </title> <link href="../../TheosStyle.css" rel="stylesheet" type="text/css"><link rel="shortcut icon" href="../../TT_ICO.png" /></head> <BODY> <CENTER> <div id="header"><HR><h1>Theo Todman's Web Page - Paper Abstracts</h1><HR></div><A name="Top"></A> <TABLE class = "Bridge" WIDTH=950> <tr><th><A HREF = "../../PaperSummaries/PaperSummary_00/PaperSummary_111.htm">Counterpart Theory and Quantified Modal Logic</A></th></tr> <tr><th><A HREF = "../../Authors/L/Author_Lewis (David).htm">Lewis (David)</a></th></tr> <tr><th>Source: Lewis - Philosophical Papers Volume I, Part 1: Ontology, Chapter 3</th></tr> <tr><th>Paper - Abstract</th></tr> </TABLE> </CENTER> <P><CENTER><TABLE class = "Bridge" WIDTH=600><tr><td><A HREF = "../../PaperSummaries/PaperSummary_00/PaperSummary_111.htm">Paper Summary</A></td><td><A HREF = "../../PaperSummaries/PaperSummary_00/PaperCitings_111.htm">Books / Papers Citing this Paper</A></td><td><A HREF="#ColourConventions">Text Colour-Conventions</a></td></tr></TABLE></CENTER></P> <hr><P><FONT COLOR = "0000FF"><FONT COLOR = "800080"><ol type="1"><li>In this landmark paper, Lewis outlines his theory of <a name="1"></a><A HREF="../../Notes/Notes_1/Notes_121.htm">modality</A><SUP>1</SUP> and counterparts. The eight postulates constitutive of Lewis's counterpart theory are expressed in an extensional first-order language that replaces the <a name="2"></a><A HREF="../../Notes/Notes_1/Notes_121.htm">modal</A><SUP>2</SUP> operators (characteristic of traditional quantified <a name="3"></a><A HREF="../../Notes/Notes_1/Notes_121.htm">modal logic)</A><SUP>3</SUP> with four primitive predicates: <BR>& 'x is a possible world', <BR>& 'x is in possible world y', <BR>& 'x is actual', and <BR>& 'x is a counterpart of y'. </li><li>Upon presenting a scheme for translating sentences expressed in quantified <a name="4"></a><A HREF="../../Notes/Notes_1/Notes_121.htm">modal logic</A><SUP>4</SUP> into those expressed in his preferred extensional language, Lewis demonstrates that the latter is nevertheless a richer language; while every sentence of quantified <a name="5"></a><A HREF="../../Notes/Notes_1/Notes_121.htm">modal logic</A><SUP>5</SUP> may be translated into a sentence expressed in counterpart theory, the reverse is not the case. </li><li>Lewis concludes the paper by considering the implications of his view for several well-known topics (notably, Aristotelian essentialism). </li><li>The postscript includes numerous additions and emendations (including a specification of the primitive predicate, 'x is in possible world y').</li></ol><hr><FONT COLOR = "0000FF"><B>Comment: </B><BR><BR>Also in <a name="6"></a>"<A HREF = "../../BookSummaries/BookSummary_06/BookPaperAbstracts/BookPaperAbstracts_6554.htm">Loux (Michael), Ed. - The Possible and the Actual: Readings in the Metaphysics of Modality</A>".<BR><FONT COLOR = "0000FF"><HR></P><a name="ColourConventions"></a><p><b>Text Colour Conventions (see <A HREF="../../Notes/Notes_10/Notes_1025.htm">disclaimer</a>)</b></p><OL TYPE="1"><LI><FONT COLOR = "0000FF">Blue</FONT>: Text by me; &copy; Theo Todman, 2018</li><LI><FONT COLOR = "800080">Mauve</FONT>: Text by correspondent(s) or other author(s); &copy; the author(s)</li></OL> <BR><HR><BR><CENTER> <TABLE class = "Bridge" WIDTH=950> <TR><TD WIDTH="30%">&copy; Theo Todman, June 2007 - August 2018.</TD> <TD WIDTH="40%">Please address any comments on this page to <A HREF="mailto:theo@theotodman.com">theo@theotodman.com</A>.</TD> <TD WIDTH="30%">File output: <time datetime="2018-08-03T00:10" pubdate>03/08/2018 00:10:59</time> <br><A HREF="../../Notes/Notes_10/Notes_1010.htm">Website Maintenance Dashboard</A></TD></TR> <TD WIDTH="30%"><A HREF="#Top">Return to Top of this Page</A></TD> <TD WIDTH="40%"><A HREF="../../Notes/Notes_11/Notes_1140.htm">Return to Theo Todman's Philosophy Page</A></TD> <TD WIDTH="30%"><A HREF="../../index.htm">Return to Theo Todman's Home Page</A></TD> </TR></TABLE></CENTER><HR> </BODY> </HTML>