ILLUSTRATIONS:
| Constructive Hypothetical Syllogisms. | |
| Symbols. | Words. |
| If A is B, C is D | If you are diligent, you will succeed; |
| A is B | And you are diligent, |
| ∴ C is D | Therefore you will succeed. |
| Destructive Hypothetical Syllogisms. | |
| If A is B, C is D | If you had been diligent, you would have succeeded; |
| C is not D | But you did not succeed, |
| ∴ A is not B | Therefore you were not diligent. |
5. THE RULE AND TWO FALLACIES OF THE HYPOTHETICAL ARGUMENT.
From a given hypothetical proposition it is possible to construct four different hypothetical syllogisms, as the attending illustrations make evident:
Consider the hypothetical proposition “If it has rained, the ground is damp.”
(1) Minor premise affirms antecedent.
If it has rained, the ground is damp;
It has rained,
Therefore the ground is damp.
(2) Minor premise denies antecedent.