A powerpoint to support learning some of the basics of arguments and how they work. Includes a visual version of the Monty Python 'But how do you know she's a witch?' argument as an example of bad argument.

1. Arguments
A falasafaz! presentation
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2. Which arguments?
Not this More like this
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3. Defining Arguments
An argument is a connected series of statements
intended to establish a proposition.
Reasons – and the relations between them –
determine whether we should logically accept a
particular conclusion. 3

4. Activity #1
Using the video (click
here or the witch):
What reasons are
offered to logically
support the conclusion
that ‘she is a witch’?
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5. How do you know she’s a
witch?
(1) She looks like a witch – she’s
dressed like a witch, is
wearing a pointy hat, has a
pointy nose, and she even
has a wart. Therefore, she’s a
witch.
Problem: The villagers dressed
her as a witch. Not only is her
looking like a witch an illusion,
but it isn’t one she’s responsible
for.
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6. How do you know she’s a
witch?
(2)She turned the villager
into a newt (even
though he got better).
Problem: ????
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7. How do you know she’s a
witch?
You burn witches You also burn wood
So witches must
burn because
they’re made of
wood
But how do we
know she’s made
of wood?
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8. How do you know she’s a
witch?
NO.
You can make bridges out of
stone or wood, so making a
bridge out of her won’t tell
you if she’s wood.
But! As well as burning, wood
also floats.
Ducks also float. Therefore…
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Make a bridge out of her?

9. How do you know she’s a
witch?
If the woman weighs the
same as a duck…
Then she’s a witch.
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10. Recap on arguments
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Reasons
Inference Assumptions
Conclusions
Implications

11. Evaluating arguments?
• Are the reasons
true?
• Are the reasons
relevant and
significant to the
conclusion?
• Is the inference
valid?
• Is the conclusion
plausible?
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