It’s a surprise!
Department of Informatics
University of Sussex
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E-Intentionality, PAICS Research Group, Department of Informatics
University of Sussex, June 1st 2006
• Why is the title of this talk "It's a
• It's a surprise!
…some logic (groan)
Logic: What is it good for?
• One application: To make explicit
the logical structure of an
• Then it becomes a
mechanical/syntactic matter to
determine, e.g. validity
• Ron says: "All men are mortal.
Socrates is a man. Therefore, Socrates
• Michael says: "Every man is mortal.
Socrates is a man. Thus, Socrates is
• Blay says: "All men are mortal.
Schwarzenegger is a man. Therefore,
Schwarzenegger is mortal."
• Different words, but same logical form…
• So if one of the arguments is valid, the
• This logical form is valid.
• Either logical form does not
determine validity (a
contradicition, or damn near it),
• Standard means of translating
arguments into their logical form
• Consider: "Ron has drawn 10
conclusions today. 10 is less than 11.
Therefore, Ron has drawn fewer than
11 conclusions today."
C(R,t) = 10
10 < 11
C(R,t) < 11
• Is this valid?
• Perhaps for you, but not for me!
• The problem is that carrying out the
inference interacts with the truth of the
premises of the inference
• So either we need to say that validity
does not supervene on logical form, or
the foregoing is not the logical form
Embodied logical form
• But what is the logical form, then?
• Needs to include the person who is
carrying out the inference?
• What else? Timing? Order?
Connection to paradoxes
• Moore’s paradox:
– “Ron cannot know this sentence to
• Gödelian argument
• Newcomb’s problem
• Liar paradox
• Rationality paradox/prisoner’s