Linear Setup Practice Drill #9

[bjennings]

How do I tell the difference between could be true and must be true not laws? For instance, conditional statement if/then. Some not laws exist only after another variable is placed and are then considered could be true not laws. How do I distinguish these from must be true not laws which would always not be true regardless of variable arrangement?

[Dave Killoran]

Hi Bjennings,

Thanks for the question! The way I look at Not Laws are that they always represent something that is constant. So, when you see Not Laws on any global diagrams in the LGB, you are looking at something that always is the case. The "could be true" Not Laws you mention, or, in other words, the ones that only happen in some cases, aren't global and thus I wouldn't show them on my main diagram (specifically to avoid the confusion between what only happens sometimes and what happens always). I would handle those "occasional" Not Laws two ways: first I'd simply diagram the rule off to the side in my rule list and second I'd then wait until a question locally enacted that rule and then I'd show the Not Law(s) on any mini-diagram I made for that question. That way I avoid commingling the two types and avoid assuming that an occasional Not Law is a constant.

If I missed the point of your question, please let me know. In #9 I don't see a conditional rule or a problem like the one you describe, but maybe I'm looking at the wrong thing. If you have a specific question you want to look at where this was an issue, by all means let me know and we can take a closer look at that.

Thanks!