3. At Least One
If A is not selected then, then B must be chosen. You can then take the contrapositive: If B is not selected, then A must do it.
Now we’re going to introduce a new concept: combining conditionals. See this example (shown in the next video):
If Matt is NOT in the Office, then Tim is:
~M → T
Contrapositive of #1: If Tim is NOT in the Office, then Matt is.
~T → M
At least Tim or Matt must be at the office. Note: There’s nothing ruling out T and M being together.
Either you run the day or the day runs you.
~ RTD (run the day) → DRY (day runs you)
Contrapositive:~ DRY → RTD
- Now that you can combine statements, we can do more complex deductions, such as If and Only If.
Next LSAT: March 30th