View source for Philosophy:Ramsey–Lewis method

{{Short description|Method for defining terms found in theoretical frameworks}}
The '''Ramsey–Lewis method''' is a method for defining terms found in [[Theory|theoretical framework]]s (such as in [[Scientific theory|scientific theories]]), credited to [[Biography:Frank P. Ramsey|Frank P. Ramsey]]<ref>{{harvnb|Ramsey|2013}}</ref> and [[Biography:David Lewis (philosopher)|David Lewis]].<ref>{{harvnb|Lewis|1970}}</ref> By using this method, a set of theoretical terms appearing in a [[Theory|theory]] can be defined implicitly by the assertions of the theory itself.

==Overview==
A [[Scientific theory|scientific theory]] which attempts to describe "[[Physics:Electron|electron]]s" is inherently abstract, as no one has ever observed an electron directly. Thus, the origin and content of the concept of "electron" is questionable. What does the word exactly signify? Ramsey and Lewis proposed that the meaning of the term "electron" is implicitly generated by the scientific theory that describes it, via all its assertions about electrons. Electrons are those things about which all the statements of the theory are true.

However, some of those statements in a theory refer to other unobserved entities and properties such as "charge" or "spin". For instance, "Electrons attract [[Physics:Proton|proton]]s" and "Electrons have negative charge" employ the terms "protons" and "negative charge" (with the latter also implicitly using the concept of "charge"). These properties are formalized, statements (such as [[Causality|conditionals]]) are formed using them, and those statements taken together are the [[Philosophy:Definition|definition]] of the term.

Consider a sentence such as "There's an electron in the sink." This means something along the lines of: "There exist some properties ''P''<sub>1</sub>,&nbsp;''P''<sub>2</sub>,&nbsp;...,&nbsp;''P''<sub>''n''</sub> ( one for every theoretical property involved in the scientific theory, with 'electronhood' (which roughly corresponds to the [[Philosophy:Essence|essence]] of an [[Physics:Electron|electron]] included as ''P''<sub>1</sub>) such that... (a statement in the scientific theory, but with ''P''<sub>1</sub>,&nbsp;...,&nbsp;''P''<sub>''n''</sub> substituted for the specific terms such as 'charge', 'is an electron', etc. employed by the theory), and there is something in the sink that has ''P''<sub>1</sub>."

The process of converting the narrative form of a scientific theory into [[Philosophy:Second-order logic|second-order logic]] is commonly called "Ramsification" (sometimes also spelled "Ramseyfication").

Example: Suppose there are only three principles in our scientific theory about electrons (those principles can be seen to be statements involving the properties):

A1. Electrons (things that have P1) have charge (P2).

A2. Things with charge (P2) tickle you.

A3. Electrons (things that have P1) cause lightning.

Furthermore, we include the property of "electronhood", as outlined above, to be designated by ''P''<sub>1</sub>, and the property of "charge" to be designated by ''P''<sub>2</sub>.

Then the meaning of a sentence such as "I have an electron in my pocket" is Ramsified into:

"There are properties ''P''<sub>1</sub> and ''P''<sub>2</sub> such that (things with ''P''<sub>1</sub> also have ''P''<sub>2</sub>, and things with ''P''<sub>2</sub> tickle you, and things with ''P''<sub>1</sub> cause lightning, and there is a thing with ''P''<sub>1</sub> in my pocket)." ({{harvnb|Toraldo di Francia|1981|p=74}}, who cites {{harvnb|Ramsey|2013}}.)

==Notes==
<references/>

==Sources==
*{{Citation| first=Giuliano | last= Toraldo di Francia| title=The Investigation of the Physical World| location=Cambridge| publisher=Cambridge University Press| year=1981| isbn=0-521-29925-X |page=74 |chapter=2. The physics of the reversible §2.8 Do magnetic charges exist? |chapter-url=https://archive.org/details/investigationofp0000tora/page/74/mode/1up |quote=... At this point, we can mention a procedure, usually named after F.P. Ramsey (Ramsey, 1954; see also Sneed, 1971, Chaps, 3 and 4). We should also try to discuss only the gist of the procedure rather than all the technical details. Every time a theoretical term appears in a theory one should substitute a variable ''x'' for it, and the theory should be preceded by the expression "there exists a certain thing ''x'', such that."}}
**Originally published as  {{citation |author-mask=1 |first=Giuliano |last=Toraldo di Francia |title=L'Indagine del Mondo Fisico |publisher=Giulio Einaudi |year=1976 |isbn=9788806447502 |oclc=762196245 |series=Nuova biblioteca scientifica Einaudi |url=}}
*{{Citation|last=Lewis|first=David |year=1970|title=How to define theoretical terms |journal= Journal of Philosophy |volume=67 |issue=13 |pages=426–446 |doi=10.2307/2023861 |jstor=2023861}} 
*{{Citation|last=Ramsey|first=Frank P. |year=2013 |orig-year=1931 |title=The Foundations of Mathematics | publisher=Taylor & Francis |isbn=978-1-134-52810-3}} as cited by {{harvnb|Toraldo di Francia|1981|p=74}}

==External links==
• [http://www.jimpryor.net/teaching/courses/mind/notes/ramseylewis.html An outline of the Ramsey–Lewis method]

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[[Category:Philosophy of science]]

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