# Economics Dictionary of Arguments

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Similarity metrics: a measure of similarity. It is a problem in relation to possible worlds that it is not always determinable which one of two worlds is closer in relation to a third.
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Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments.

Author Concept Summary/Quotes Sources

David K. Lewis on Similarity Metrics - Dictionary of Arguments

V 10
Similarity metric/Possible worlds/Po.wo./Similarity/Lewis: order assumption: weak order: whenever two worlds can be accessed from the the world i in question, either one or the other is more similar to world i. - Decreasing or increasing similarity is transitive. - In contrast, partial order: not all couples are distinguishable.
>Possible world/Lewis
.
V 11
Compatibility/Possible world/Lewis: B is compatible with A in world i if an A world is closer to i than any non-B-world. - (Reversal of rather true) - then A were>>would C is true if C follows from A together with auxiliary hypotheses B1...Bn. - E.g. natural laws are compatible or completely incompatible with every assumption - thesis: then laws of nature are generalizations of what we consider to be particularly important. - Then conformity with Laws of Nature should be important for the similarity relation between possible worlds - (> Similarity metrics).
V 12f
Similarity metric/Possible worlds/Lewis: sphere/Similarity sphere: E.g. S sphere around the world i: exists, if any S world is accessible from i and closer than any ~ S world): admitting A: a sphere contains an A world. - Degree: spheres represent degrees (comparative, unlike neighborhood in topology). Compatibility/Compatible/(s): B is compatible with A if there is an A world in the B sphere. - Definition A were>>would C is true if A>C applies in an A permitting sphere around i, if such a sphere exists. >Implication.
V 13
Definition Then were A>>would C would be true if AC applied in every A permitting sphere around i ((s) conjunction) - Definition A impossible worlds: >Impossible World.
V 42
Similarity metric/Similarity/Possible world/Lewis: It is not about any particular similarity relation that you happen to have in mind. - Problem: if some aspects do not even count, the centering assumption would be violated. - I.e. worlds that differ in an unnoticed aspect, would be identical with the actual world. - Lewis: but such worlds do not exist.-
Similarity relations: must be distinguished: a) for explicit judgments - b) for counterfactual judgments.
V 150
Revision/Possible world/Similarity metrics/Stalnaker/Lewis: every revision will select the most similar antecedent world.
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Schwarz I 160
Lewis: E.g. a single particle changes its charge: then it behaves differently. - Because a possible world in which not only the charge but also the role were exchanged would be much less similar (> next world).

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Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. Translations: Dictionary of Arguments
The note [Concept/Author], [Author1]Vs[Author2] or [Author]Vs[term] resp. "problem:"/"solution:", "old:"/"new:" and "thesis:" is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.

Lewis I
David K. Lewis
Die Identität von Körper und Geist Frankfurt 1989

Lewis I (a)
David K. Lewis
An Argument for the Identity Theory, in: Journal of Philosophy 63 (1966)
In
Die Identität von Körper und Geist, , Frankfurt/M. 1989

Lewis I (b)
David K. Lewis
Psychophysical and Theoretical Identifications, in: Australasian Journal of Philosophy 50 (1972)
In
Die Identität von Körper und Geist, , Frankfurt/M. 1989

Lewis I (c)
David K. Lewis
Mad Pain and Martian Pain, Readings in Philosophy of Psychology, Vol. 1, Ned Block (ed.) Harvard University Press, 1980
In
Die Identität von Körper und Geist, , Frankfurt/M. 1989

Lewis II
David K. Lewis
"Languages and Language", in: K. Gunderson (Ed.), Minnesota Studies in the Philosophy of Science, Vol. VII, Language, Mind, and Knowledge, Minneapolis 1975, pp. 3-35
In
Handlung, Kommunikation, Bedeutung, Georg Meggle, Frankfurt/M. 1979

Lewis IV
David K. Lewis
Philosophical Papers Bd I New York Oxford 1983

Lewis V
David K. Lewis
Philosophical Papers Bd II New York Oxford 1986

Lewis VI
David K. Lewis
Convention. A Philosophical Study, Cambridge/MA 1969
German Edition:
Konventionen Berlin 1975

LewisCl
Clarence Irving Lewis
Collected Papers of Clarence Irving Lewis Stanford 1970

LewisCl I
Clarence Irving Lewis
Mind and the World Order: Outline of a Theory of Knowledge (Dover Books on Western Philosophy) 1991

Schw I
W. Schwarz
David Lewis Bielefeld 2005

> Counter arguments against Lewis
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