Hmm, lets take a look at this.. Technically it's not the same kind of conditioning, since Pavlov's dogs are an example of classical conditioning. I think it might be more helpful to see where the logic breaks down here.
The reasoning is if A then B, if B then C. So if A, then C. In other words, if A is true, then B is true. If B is true, then C is true. Since A is true then if follows that C is true.
In this case, the reasoning is basically if it's from the Watchtower, (A) it's God's counsel. (B)
If God gives counsel, (B) then I obey. (C)
So if the Watchtower says something, (A) then I obey. (C)
Now the problem of course lies between A and B. You kind of forget about that leap and start thinking of it in two parts, (A and C)because it goes without saying that the Watchtower is God's channel of communication, or so you think.
The logic of A to B which states the Watchtower speaks God's counsel is probably from a bit of inductive reasoning, which is where you have a certain amount of evidence (or what you consider evidence) that leads you to a certain conclusion. Of course there's a lot of things we can get into, like faulty premises in considering some things as reasons to believe a given organization speaks for God, but the important thing to note here is that even if all of the premises are true it is NEVER a certainty when you use inductive reasoning, it is only more PROBABLE because of the amount of evidence you have gathered, which of course is usually very subjective.
So basically, you're going from a bit of reasoning (inductive) that is not definite to one that is, (deductive) since the latter is pretty much a mathematical fact. It is like saying if I have two dimes, then I have $0.25. If I have $0.25, then I can change it into a quarter. Well, since a dime is only $0.10 it just does not add up to $0.25. While the monetary value in the example is small, the claim that any organization or what/whoever speaks for God is not small. In any case, it just does not add up.
Edited to add:
It should be noted that as much evidence as you think you have in inductive reasoning, it may not be enough just because you think it is. You might think 10 reasons are plenty, but if the total list of criteria is say 50, or anything greater than 10, then it's not true. But the bottom line is since inductive reasoning is not absolute, and you're plugging that into a piece of deductive reasoning, then it does not hold that the conclusion you reach through that bit of deductive reasoning is true, because you can't be sure your shopping list of evidence is all that is needed to prove things conclusively.
I'd like to open this up just as Jerome did, did I miss anything?