- Posts: 9
- Joined: Jul 30, 2020
I hope you could help me to clarify diagramming of inferences and the inferences themselves. LGB 2019 edition, pages 76-77, is the source. Thank you for your time and help.
(1) Is it correct to diagram the second inference in #10 this way: J2 -> K1 rather than K1 -> J2? Is it correct to diagram the second inference in #11 this way: F1 -> G2 rather than G2 -> F1 ? Is there any difference? I feel that it may be wrong because I may have switched the sufficient and necessary conditions in these examples.
(2) If we were to apply the “Note” rules from #10 to #12 and had to draw inferences from the original statement of #12, would it be correct to conclude that #12 has the following two inferences: C7 -> A6 and C2 -> A1 ?
(3) You mentioned previously that inferences can be drawn from either an original statement or a contrapositive, as they are logically identical. I feel that sometimes it is easier to draw the inferences only from the original statement (e.g., #10) or from both the original statement and contrapositive (e.g., #11). Does it take practice and exposure to more logic games in order to easily draw all the existing inferences from either the original statement or contrapositive, and not both?
(4) Do I have the right thought process about making the inferences in #11 based on the original statement alone?
The original statement in #11 states: If G is cleaned before F, then F is cleaned second. It means that in this example we have only two letter variables “G” and “F” and only two time/order variables which are “first” and “second”. Since “no ties” are possible in this example, it means that both “G” and “F” cannot be cleaned at the same time as either “first” or “second”. In other words, if G is cleaned first then F can be only cleaned second, and vice versa. That is why we have only two inferences based on the original statement: If F is cleaned second then the only remaining time/order variable for G is first, and vice versa.
Thanks again for your time and help.