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It is false that it is day and it is night.
It is day.
Therefore, it is not night.//-3Unsyllogistic are those which are persuasively similar to syllogistic argu-
ments, but do not conclude [validly], for example,
If Dion is a horse, Dion is an animal.
But Dion is not a horse.
Therefore, Dion is not an animal.- Again, of arguments some are true, some false. True arguments,
then, are those which conclude [validly] by means of true premisses,
for example,
If virtue is helpful, vice is harmful.
<But virtue is helpful.
Therefore, vice is harmful.>False arguments are those having at least one false premiss or those which
are non-conclusive, for example,
If it is day, it is light.
It is day.
Therefore, Dion is alive.And there are possible arguments and impossible and necessary and non-
necessary. And there are indemonstrable arguments, because they do not
need demonstration, different ones being given by different authors. In
Chrysippus there are five, through which every argument is formed.
These are used in conclusive arguments, in syllogisms and in mode-
arguments.
- The first indemonstrable is that in which every argument is made
up of a conditional and the antecedent from which the conditional begins,
and concludes to the consequent, for example,
If the first, the second.
But the first.
Therefore, the second.