Invalid Argument/Examples/Moon is Yellow

Example of Invalid Argument

This argument is invalid:

The moon is yellow.

Therefore, the moon is made of cheese.

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.

$\blacksquare$

1988: Alan G. Hamilton: Logic for Mathematicians (2nd ed.) ... (previous) ... (next): $\S 1$: Informal statement calculus: $\S 1.1$: Statements and connectives