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Logic: Language and Informatio
1-1-1 Propositions
Greg Restall
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What isLogicall about?
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What isLogicall about?
One answer Propositions, and
relationships between them.
consistency
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What isLogicall about?
One answer Propositions, and
relationships between them.
consistency
consequence
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What isLogicall about?
One answer Propositions, and
relationships between them.
consistency
consequence
equivalence
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Example Propositions
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Example Propositions
A sentence expresses a propositionif it makes some statement
about how things are.
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Example Propositions
A sentence expresses a propositionif it makes some statement
about how things are.
We have students from all over the world.
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Example Propositions
A sentence expresses a propositionif it makes some statement
about how things are.
We have students from all over the world.
There is no difference between the mind and the brain.
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Example Propositions
A sentence expresses a propositionif it makes some statement
about how things are.
We have students from all over the world.
There is no difference between the mind and the brain.
3+ 5 < 4+ 3.
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Example Non-Propositions
Not all sentences express propositions.
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Example Non-Propositions
Not all sentences express propositions.
Please dont watch these lectures while driving a car.
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Example Non-Propositions
Not all sentences express propositions.
Please dont watch these lectures while driving a car.
What is the capital of Ethiopia?
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Example Non-Propositions
Not all sentences express propositions.
Please dont watch these lectures while driving a car.
What is the capital of Ethiopia?
Thank goodness; the poor cat!
l
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Example Non-Propositions
Not all sentences express propositions.
Please dont watch these lectures while driving a car.
What is the capital of Ethiopia?
Thank goodness; the poor cat!
Hi, Jen!
H d ll hi h i i
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
H d ll hi h i i
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
A propositionis the kind of thing you could:
H d ll hi h i i
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
A propositionis the kind of thing you could:
believeordisbelieve;
H d t ll hi h t iti
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
A propositionis the kind of thing you could:
believeordisbelieve;
agreeordisagreewith;
H d t ll hi h t iti
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
A propositionis the kind of thing you could:
believeordisbelieve;
agreeordisagreewith;
assertordeny;
How do we tell which sentences express propositio
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
A propositionis the kind of thing you could:
believeordisbelieve;
agreeordisagreewith;
assertordeny;
give a reasonfororagainst;
How do we tell which sentences express propositio
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How do we tell which sentences express propositio
Here are guidelines for distinguishing sentences that expresspropositions from those that dont:
A propositionis the kind of thing you could:
believeordisbelieve;
agreeordisagreewith;
assertordeny;
give a reasonfororagainst;
use as a reasonfororagainstsomething else; and
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Exercise
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Exercise
Exercise
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Exercise
Which of these sentences express propositions?
Greg lives in Melbourne.
What do you think of logic so far?
I wish I had learned logic before!
Its immoral to consume meat.
This last sentence on the list is not true.
Next Up: Connectives and Combining Propositio
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Next Up: Connectives and Combining Propositio