Transcript Logic of Fiction and Logic in Computer Science

Logic of Fiction and
Logic in Computer
Science
Chayunt Mathon
Department of Philosophy, Chulalongkorn University
Thailand
Fictions
Fictional Discourse
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Fictive Discourse
Metafictive Discourse
Transitive Discourse
Theories of Fiction
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Ontological Analysis
Fictive-operator Analysis
Pretense, Imagination, and Make
Believe Analysis
Fictional Discourse
[Woods and Alward, 2004] though that the below aspects of fiction are axiom of naïve theories of
fictionality or our pre-theoretic intuitions regarding fictions.Reference is possible to fictional beings even
though they do not exit.
A.
B.
C.
D.
E.
Some sentences about fictional beings and events are true.
Some inference about fictional beings and events are correct.
These three facts are name possible, in a central way, by virtue of the
creative authority of authors of fiction. Indeed, the primary and
originating criterion of truth for fictional sentences is the author’s sayso.
These three facts are name possible, in a central way, by virtue of the
creative authority of authors of fiction. Indeed, the primary and
originating criterion of truth for fictional sentences is the author’s sayso.
It is possible for a fictional truth to make reference to real things. For
example, “Sherlock Holmes lived in London” is true and refers to the
actual capital city of England.
Ontological View
This view believes that sentences of fictional and non-fictional discourse have the same logical
form, but a distinct range of entities serve as the semantic values of fictional and non-fictional
expressions. The exemplars are:
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Qusasi-actualist Meinongean accounts of the referents of fictional names ([Parsons, 1975]
and [1980] and [Routley, 1979] and Cf. [Castaneda, 1979] and [Zalta, 1983]). The version of
Parsons’ correlated with each non-empty set of properties a distinct, specific object; existent and
non-existent. Fictional objects are a subclass of the class of non-existent objects. They are the
objects correlated with sets of the following sort, where x is a fictional object:
x = the object correlated with {p: according to the relevant body of literature, x has p}.
An example of this scheme is {p: according to the Conan Doyle stories, Sherlock Homes has p}.
The consequence of such treat is that, fictional objects can enter to a sentence or the like and
make it to have truth-value “true”.
Fictive-Operator Analysis
This view believes that sentences of fictional and non-fictional discourse have different logical form. The sentences of fictional discourse are analyzed in
term of tacit or explicit fictive operator. Each of the approach differs in interpretation of fictive operator. But their general scheme or logical form is
It is true-in-t that 
Where t is fictional text and  is fictional sentence. For example, “It is true-in-the-Holmes-stories that Sherlock Holmes was a detective.” The exemplars are:
 Possible world
fictional discourse is:
analyses ([Plantinga, 1974] and [Kaplan, 1973] and [Gabriel, 1979] and[Lewis, 1983]). The version of Lewis’ truth theory of the
A sentence of the form “It is true-in-t that ” is true iff  is true at every world where t is told at known fact
rather than
fiction.
For example, “It is true-in-the-Holmes-stories that Sherlock Holmes was a detective” is true just in case at all possible worlds in which the Holmes stories are
told as known fact, the occupant of the Holmes-role is detective.
 Fictional world analyses ([Howell, 1979] and [Pavel, 1986] and [Woltersdorff, 1980]). Simply, fictional worlds are worlds of fiction, but they
need not be consistent, even need not be complete. Such analyses interpret fictive operator as:
“It is true-in-t that ” is (actually) true just in case  is true at all of the fictional worlds determined by t.
 Non-referential, substitutional-quantificational accounts [Woods, 1974]. The version of Woods’ truth theory of the fictional discourse is:
A sentence of the form “It is true-in-t that ” is true just in case either (1)  occurs in t or (2)  can be derived from sentences
through repeated application of fictional-inference rule.
 Propositional
analyzed as;
that occur in t
attitude approaches [Curries, 1990]. Briefly, Curries would made the matefictive claim “It is true-in-t that ” to be
The fictional author of t believes that .
Where as “believe” is the attitude and fictional author is the subject of the attitude Cuuries chooses respectively.
Imaginative Analyses
This group of views is analyzed in term of some kind of imaginative activities. According to this kind of analyses, storytellers do not assert the sentences
they utter, nor do readers believe the sentences they encounter, they get “involved in the story” in certain way.
 Authorial pretense analyses [Searl, 1975]. The version of Searl’s truth theory of the fictional discourse is:
Authors do not assert sentences they utter, they pretend to do so; and part of this pretense involves
pretending to refer to real individuals (in the case of the sentences contain
fictional names). In this
manner, authors create fictional characters and events. When critics or readers say that  they really refer to the
fictional entity in , they do so because
of the shared pretense.
 Reader/appreciator make-believe analyses [Walton, 1990]. According to the version of Walton, games of
make-believe are rule-governed activities. Such rules prescribe that particular propositions be imagined. These
are the fictional truths of the game. A prop in a game of make-believe is an object that, in virtue of the rules
of the game, generates fictional truths. Here is his theory:
truly
A sentence of the form “It is true-in-t that S” is true iff fiction t is such that one who engages
in pretense of kind K in a game authorized for it makes it fictional of herself that she
speaks
For example: “it is true-in-The Hound of the Baskervilles that Holmes was a detective” has to be paraphrased as
“The Hound of the Baskervilles is such that one who engages in pretense of kind K in a game authorized for it to
makes it fictional of herself that she speaks truly.”
Nature of Fictions
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“A fiction is a made-up story.”
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“There’s no one “right” way to read a piece of fiction. There are many good
ways. This does not mean that anyone’s reading of a piece of fiction is equal
to anyone else’s. There are better and worse reading, depending on how well
readers can attune themselves to the story, on how carefully they have looked
at the language, become aware of the tone, understood the theme, notice
patterns of imagery, and, in general, become quite and really listened to a
separate human being. But given equal attention and sensitivity to a story,
there are many legitimate approaches.” (Clayton, John J. (2000) The Heath Introduction to Fiction )
(Scholes, Robert (1991) Element of Literature)
Structure of Formal logical System
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Grammar: formal Language/symbols
Deductive Apparatus: axiom(s)/ Rules of
Inference
 Proof Theory
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Semantics: Interpretations of formal language
Historical sematics approach of
Logic of Fiction
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We, intuitively, can valuate a metafictive proposition to
be TRUE
Denying the Objectual Interpretation of Classical Logic
(only FALSE value can be given for a metafictive
proposition)
The relevant semantics is ordinary Model-Theoretic
A metafictive proposition can be TRUE because of an
aspect of Correspondence Theory of Truth; the story
say so or the author say so.
Historical systematic approach to
the Logic of Fiction
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Woods, John (1974), The Logic of Fiction: Philosophical Sounding of Deviant Logic
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.
.
Nossum, Rolf (2003), ‘A Contextual Approach to the Logic of Fiction’, LNAI 2680
.
.
.
Woods, John and Peter Alward (2004). “The Logic of Fiction” In Gabbay, D.
M. (ed.), Handbook of Philosophical Logic
Logic of Fiction vs. logics in
computer science
Logic in computer science
:topics where logic is applied to computer science and artificial intelligence
: logic has important role in some area of computer science in general and AI in particular
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Unconcerned logics: Boolean Logic, Fuzzy Logic, Quantum
Logic, etc.
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Concerned logics:
- Common Sense Logicism [including narrative
understanding] (AI); John McCarthy
- The Default based logics/kinds of
Nonmonotonic Logics; Belief Revision (AI);
Closed –world reasoning (Database of
computer science); Rational Planning
Woods, John and Peter Alward
(2004). “The Logic of Fiction”
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Take the ordinary Model-Theoretic Semantics.
Yet
In Proof Theory; proposed
1. default [(Reiter, 1980); (Makinson, 1993) …) as
Generic proposition (The default that Holmes has a skin is derived
from the generic proposition that humans have skins + Holmes is a human.)
2. Implicatures [(Grice, 1989); (Levinson, 2000)]
as speaker’s common knowledge
Monotonic-Nonmonotonic Logics
Monotonic Logic
- Aristotelian logic
- Classical logic
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- deal only with patterns of
inference that hold
without exception
Nonmonotonic Logics
- It is reasonable to ignore
outlandish possibilities.
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Default based logic
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To ignore outlandish possibilities is to have
default(s).
Manipulate some Default Rule; for example
-
General form:
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In the presence of {A1,…,An} and in the absence of {B1,…,Bn}, conclude C.
-
Normal default form: General form:
In the presence of {A1,…,An} and in the absence of -C, conclude C.
Recall
(Clayton, John J. (2000) The Heath Introduction to
Fiction )
“There’s no one “right” way to read a piece of fiction. There are
many good ways. This does not mean that anyone’s reading of a
piece of fiction is equal to anyone else’s. There are better and
worse reading, depending on how well readers can attune
themselves to the story, on how carefully they have looked at the
language, become aware of the tone, understood the theme,
notice patterns of imagery, and, in general, become quite and
really listened to a separate human being. But given equal
attention and sensitivity to a story, there are many legitimate
approaches.”
AND
Need of ordinary Model-Theoretic
What should we concern in logics in
Computer Science?
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No: values; 0, 1
No: Physical status of 0/1 values, 0v., 5v
Yes: the informal reading of the values 0, 1 (the
informal semantics)
Informal semantics approach
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Logic of Fiction (Philosophical)
= many values logic, bivalence logic with truth
valueless proposition (?), mixed semantics (at least
one of them must be ordinary Model-Theoretic)
≠ ordinary Model-Theoretic with default based
proof theory
logic of fictions (Computer Science/AI, default based )
= Non-ordinary Model-Theoretic semantics; for
example, Preference Model-Theoretic, others
≠ sole ordinary Model-Theoretic (because of the nature of
fictions human should care)