Hi Srr,
Thanks for the question! The makers of the LSAT treat the word "or" in a strict logical sense: it always allows for the possibility of both occurring
unless statements or circumstances preclude the possibility of both. So, a simple statement such as "If A occurs, then B or C occurs" automatically implies that it is
possible that both B and C occur when A occurs.
What stops that possibility of both occurring? There are three separate situations you will encounter most often:
- 1. Language in the sentence that specifically precludes that outcome, such as "If A occurs, then B or C occurs but not both" or "If A occurs, then exactly one of B or C occurs." In each case, they have very directly eliminated the possibility that both B and C could occur.
2. A separate statement adds the information that both cannot occur (this appears most often in LG). For example: "If A occurs, then B or C occurs" and then another rule tells you that "B and C cannot occur together."
3. There's something inherently in the variables that disallows both of them occurring together, and you would know that they can't occur jointly via common sense public information. For example, "When Irina arrives in London, it will be night or day." Clearly, those are two states that are opposite and cannot coexist simultaneously. There are tons of possible pairings like this (rich/poor, happy/sad, small/large, increasing/decreasing, and so on) and you would naturally recognize all of them.
Hopefully that helps lock this concept down. Please let me know. Thanks!
