'Unless' Conditional Reasoning

[LSAT2018]

Just to clarify, if there is an 'unless' statement for a plural conditional statement, would this be right? I would like to clarify whether the and/or changes:

1. (A and B) unless C
Not A or Not B C

2. (A or B) unless C
Not A and Not B C

3. Not A and B unless C
A or Not B C

4. Not A or B unless C
A and Not B C

5. Not (A and B) unless C
A and B C

[Dave Killoran]

Yes, you nailed it across the board. Well done!

[LSAT2018]

Thank you for your prompt response. I was just wondering how the last part would be said in a logical reasoning stimulus. How would I know whether the Not is referring to (A and B) and not just A/B? In other words, how would I distinguish number 4 from number 5?

4. Not A or B unless C
A and Not B C

5. Not (A and B) unless C
A and B C


PS. Are there any conditional statements like this in logical reasoning/analytical reasoning sections? Please tell me if there are any, because I would love to challenge myself and try them out.

[Adam Tyson]

The language setting up those relationships would be unambiguous, LSAT2018, and for your #5 it would usually be done with a "both" structure: If both A and B occur, then C must occur. Or, in the alternative, if C does not occur, then A and B cannot both occur. The use of "both" is common. They could also just use an "and" structure: if A occurs and B occurs, then C occurs.

For #4, it would probably look somewhat obvious, too: If A does not occur, or if B does occur, then C must occur. There should be no doubt about the intended meaning, and you shouldn't make any effort to creatively interpret what you read. They should be pretty clear on their face. If you find one that isn't, let us know and we'll help you through it!