Diagramming the following sentence

[gorefighter]

Dear LSAT masters,

I have trouble thinking about the following sentence in a logical term :

"Joe, who is A, does B"

I know that you diagram this sentence as:

B (sufficient term)
A (necessary term)

B A

But why is that?
How is "Joe, who is A, does B" equivalent to saying "If Joe does B, then he is A"?

Similarly, if I tweak the example sentence a bit, "Joe, who does B, is A," now the diagram becomes:

A (sufficient term)
B (necessary term)

A B

Again, how is "Joe, who does B, is A" equivalent to saying "If Joe is A, then he does B"?

I don't understand. The only way I know how to draw these diagrams is because I just memorized them.
However, I want to understand the logic behind them.

To me,
"Joe, who is A, does B" (the first sentence) AND "Joe, who does B, is A" (the second sentence) are factually the same.

Thanks!

[Dave Killoran]

Hi Gore,

Thanks for the message! To be honest, your initial statement isn't in fact a true conditional statement. I see where you've read into it being conditional (and you've actually gotten that turned around), but by itself it's not conditional. That is probably confusing so let me explain in more detail:

• Your statement reads: "Joe, who is A, does B"
  
  Now, by itself, this just means that an entity that is an A happens to be doing B. At best that's a "some" statement because we don't know if A always does B, and we don't know the conditions of how A and B work together. What we need is an initial statement such as "If you are an A, you always do B" or some similar context to draw further conclusions. If we had that, it would appear as:
  
  Premise: A B
  Premise: AJoe
  
  Conclusion: BJoe

Now, you might also notice that I have this as likely being A B, since that's what I see as the logical background to this statement (and again, I'm forced to read a lot into this that isn't necessarily there). You reversed that diagram in your discussion, and I don't see an immediate justification for B A (unless your sentence is actually "Joe did B and is therefore an A"). So, your confusion there makes sense to me.

You mentioned you know we diagram it this way—can you point me to where you see an example of that? If there is one, there had to be more to it than the above, and if so I can explain what's happening there

Thanks!

[gorefighter]

Dear Dave

Sorry for the confusion.
When I mentioned, "...you diagram..."
I didn't mean to put a blame on the PowerScore company at all.
It's based on my memory of looking at some materials somewhere (perhaps, other than the PowerScore products).

I should've NOT relied on my memory when I was writing this post (<- NOT relying solely on one's memory is one of the important lessons I learned from your books).

Anyways, I see this type of phrase (i.e., Joe, who is A, does B) appear many times in LSAT LR section. But I never got to understand how to translate the phrase into a diagram. But thanks to you now I know.

[Dave Killoran]

Dear Dave

Sorry for the confusion.
When I mentioned, "...you diagram..."
I didn't mean to put a blame on the PowerScore company at all.
It's based on my memory of looking at some materials somewhere (perhaps, other than the PowerScore products).

I should've NOT relied on my memory when I was writing this post (<- NOT relying solely on one's memory is one of the important lessons I learned from your books).

Anyways, I see this type of phrase (i.e., Joe, who is A, does B) appear many times in LSAT LR section. But I never got to understand how to translate the phrase into a diagram. But thanks to you now I know.

Hey Gore,

Thanks, that makes sense! I was just trying to figure out where you would have seen something like this as an example, but I get it now.

Glad we were able to help!