I think the Jack / Anne / George problem was not fully formed if they want someone to come to the conclusion that 'A' is the answer.
For example, in the real world there are more "states" a person can be in than "married" or "not married". For example someone can be "separated", which IMO is not fully in the "married" or "not married" states.
To formulate the question properly it needs to say "in this make believe world, all people are either married or not married". This leads me down the path to conclude 'A' is the answer. Not without this extra bit of context.
Datashovel, man, I don't understand how being "separated" could be considered distinct from being married- it's a marital status. It's likely that they're not looking for that variable- 'married' is a binary value, why would one need to clarify?
I don't claim to know all there is to know about marriage, or all the different laws / cultures of marriage in the world throughout the entire history of human civilization. But I guess I wasn't prepared to assume that all possible situations in the world (regardless of culture, continent, country, religion, etc...) can be boiled down precisely to either "married" or "not married" states of being.
I guess I would ask: Why not include the extra context to the question?
Yes, that the married state is a boolean, is not immediately clear. However, I don't think that's why people don't consider the tree. For example, pose the same question in the form male/female.
1. Jack is looking at Anne, but Anne is looking at Eve. Jack is male, and Eve is female. Is a male looking at a female?
Although this question might even be less "boolean" than the married/unmarried one, my hypothesis is that more people will say A.
And, just a nice coincidence that my name happens to be Anne. :-)
I find it odd that there are several people who were tripped up by this, and then seem exclusively to concentrate on the whole "married/unmarried" thing.
The answer, of course, is C, because Anne might be Jack's pet dog or something and therefore isn't a person at all. :-)
For example, in the real world there are more "states" a person can be in than "married" or "not married". For example someone can be "separated", which IMO is not fully in the "married" or "not married" states.
To formulate the question properly it needs to say "in this make believe world, all people are either married or not married". This leads me down the path to conclude 'A' is the answer. Not without this extra bit of context.