Systematic reasoning - Patterns of deductive thinking
Decide whether the following disjunctive arguments are valid or invalid:
1. Either Bowser ran away or he was hit by a car.
Bowser ran away.
Therefore, Bowser was not hit by a car.
2. Either Bowser ran away or he was hit by a car.
Bowser is too smart to be hit by a car.
Therefore, Bowser ran away.
3. Either you are with us or against us.
You are not with us.
Therefore, you are against us.
1) Valid. The choice is either A (ran away) or B (hit by a car). The 'or' means that if B, then not A. ...
going from either/or to therefore. systematic reasoning and examples of disjunctive arguments