LR Bible page 491 Principle Question

[NickSabanIsGod]

Hello,

Can you explain why it is impossible to conclude that a necessary condition cannot occur? I diagrammed the principle in the question on page 491 of the LR Bible correctly as Intend Deceive or refrain from explaining a misinterpretation lie.

The explanation to why answer choice B is wrong is that "there is no premise you can add to the principle that will allow you to make the judgement that the necessary did not occur...there is no way to conclude that a sufficient condition has occured or that a necessary condition has not occured"

In the past, I would have attacked answer choice B by writing the contrapositive of the principle as -lie -intend deceive and -refrain explain misinterpret
Then I would have said B is wrong because the necessary condition for -lie had not been met. Is my old approach flawed? It is definitely more time consuming...

EDIT: would the answer to my own question be that there would be no way to CONCLUDE a necessary condition did not occur because there would be no logical chain that could lead to that conclusion even if you used to contrapositive?


Any opinions on this would be helpful. Thanks.

[Dave Killoran]

EDIT: would the answer to my own question be that there would be no way to CONCLUDE a necessary condition did not occur because there would be no logical chain that could lead to that conclusion even if you used to contrapositive?

Hey Nick,

I quoted the part above that is relevant here. In that statement, you are exactly correct—there is no way to put premises together that ultimately results in showing that the necessary condition is not occurring. You can have that as a premise, but there's no combination that allows for you to make it a conclusion.

In other words, if you start with the following:


Premise A B


Then you cannot add anything to it that forces this result:


Conclusion: B


Wait, are we sure? Let's check:

• If you add A, then you get B.
  
  If you add A, then you get nothing.
  
  If you add B, then you get A as a conclusion (note how interesting that is, you add B but that yields a different conclusion than B).

The combinations above show all possible relevant additions to the argument but none resulted in denying the necessary condition. Thus, even as we create more complex arguments, the same principles are at work and it's just a fact that you can't force it to not occur (and in the same way, you can't force a sufficient condition to occur—try it in the same way!).

So, it seems to me you found the solution on your own, but maybe the above helps flesh it out a bit more. Please let me know what you think. Thanks!