Logic

I think, in fact, that he's relying on the absence of assumptions for you to arrive at the answer. In the context of a logic problem - which is different than a word problem, or riddle - the nouns are really nothing more than placeholders; it's the relationships described between them, and often modeled "behind-the-scenes" in predicate logic, which form the basis of the puzzle.On the other hand, a riddle like "If King Midas sits on gold, who sits on silver?" depends entirely on your ability to understand and catch onto allusions to shared cultural elements.

That's sort of a creationist position - the idea that "assume no other influences" is itself a positive assumption that must be defended, rather than simply the lack of any other positive assumptions. And erroneous, as far as I can see.No other factors are assumed because no other factors are specified. The idea that it's not reasonable to dismiss unspecified factors comes from your improper assumption about Joe; that what would tend to be true about a human man - he's got a job he needs to be at, or a home in one or another city, or other factors - must neccesarily be true for the noun named "Joe."In the context of a logic problem, it doesn't matter what the word "Joe" refers to. The only qualities that are relevant to the problem are specified in the problem. That's how logic problems work.You're trying to solve a logic problem with the tools you'd use for a riddle. No wonder you have a tough time with them. The Lone Ranger.

For interest or readability.If it helps you to frame the question in that regard, and substitute variables for names, you're absolutely free to do so, because it's a logic problem. Hey, have a great time. Eat a croque monsieur for me.