Multiple Chains

[presleyclark]

My instructor used the problem:

M -F
F-US
US-NA
==========
M-F-US -NA
NA-US-F-M (this time all the letters had strikethroughs/crossed out)

Can you explain the answer to the problem? I know that every statements needs a twin and I also understand that it all connects M-F-US-NA just like A-B-C all connects.

[Jay Donnell]

Hey there!

I recognize the drill of course because it was my own example from class!

The point wasn't that there was one particular MBT answer possible to draw from the evidence, but that building the chain prepares you for any potential correct answer the choices could offer if this were from a real MBT stimulus.

If the three conditions combine to read:

Miami ----> Florida ----> United States of America ----> North America

and the contrapositive reads:

(not) North America ----> (not) United States of America ----> (not) Florida ----> (not) Miami

Then the correct answer to a MBT question could involve any term combination from either the top or the bottom chain as long as it flowed from left to right with the conditional arrow!

These are just some of the statements that have to be true and could be potential MBT answers:

Miami ----> North America
Miami ----> USA
(not) USA ----> (not) Florida
(not) North America ----> (not) Miami

The MBT question we did in class just after this drill (page 2-15 #6) had an equivalent structure with the three connectable conditional statements, and the right answer in A is the equivalent of ( ~USA ---> ~M) in this geographical example.

Hope that helps clear up any confusion you had!