Invalid Argument/Examples/Moon is Yellow
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Example of Invalid Argument
- The moon is yellow.
- Therefore, the moon is made of cheese.
Proof
Let $P$ denote the simple statement The moon is yellow..
Let $Q$ denote the simple statement The moon is made of cheese..
The argument can then be expressed as:
\(\text {(1)}: \quad\) | \(\ds P\) | \(\) | \(\ds \) | |||||||||||
\(\text {(2)}: \quad\) | \(\ds \therefore \ \ \) | \(\ds Q\) | \(\) | \(\ds \) |
There is nothing connecting the two statements.
Hence this is not a valid argument form.
$\blacksquare$
Sources
- 1988: Alan G. Hamilton: Logic for Mathematicians (2nd ed.) ... (previous) ... (next): $\S 1$: Informal statement calculus: $\S 1.1$: Statements and connectives