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Hypothetical Syllogisms
- if ... then ... statements are hypothetical
- In logic, we are really stating that
| If something is the case, then something else must be the case. |
- So the statement
| If the sky is blue, then the crickets are chirping. |
Is not really a statement of what will happen (causality), but of what must be the case (epistemology).
- So the statement
| If the lights are on, then someone is home. |
Really states that if the lights are on, you know that someone is necessarily home. Unfortunately, there is a temptation to also conclude that if the lights are not on, that no one is home. This is a fallacy that we will discover in Chapter 13 - the fallacy of Denying the Antecedent.
- A syllogism that contains one or more hypothetical statements is a hypothetical syllogism
- There are Pure Hypothetical Syllogisms, such as
If P then Q
If Q then R |
| Therefore, if P then R |
- There are also Mixed Hypothetical Syllogisms, such as
If P then Q
P |
| Therefore, Q |
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