Deductive reasoning - 101

Neighbor 1: "Hi, there, new neighbor, it sure is a mighty nice day to be moving."
New Neighbor: "Yes, it is, and people around here seem extremely friendly."
Neighbor 1: "So what is it you do for a living?"
New Neighbor: "I am a professor at the University; I teach deductive reasoning."
Neighbor 1: "Deductive reasoning-- what is that?"
New Neighbor: "Let me give you an example. I see you have a dog house out back. By that I deduce that you have a dog."
Neighbor 1: "That is right."
New Neighbor: "The fact that you have a dog leads me to deduce that you have a family."
Neighbor 1: "Right again."
New Neighbor: "Since you have a family I deduce that you have a wife."
Neighbor 1: "Correct!"
New Neighbor: "And since you have a wife, I can deduce that you are heterosexual."
Neighbor 1: "Yup."
New Neighbor: "That is deductive reasoning."
Neighbor 1: "Cool."

Later that same day

Neighbor 1: "Hey, I was talking to that new guy who moved in next door."
Neighbor 2: "Is he a nice guy?"
Neighbor 1: "Yes, and he has an interesting job."
Neighbor 2: "Oh, what does he do?"
Neighbor 1: "He's a professor of deductive reasoning at the University."
Neighbor 2: "Deductive reasoning-- what is that?"
Neighbor 1: "Let me give you an example. Do you have a dog house?"
Neighbor 2: "No."
Neighbor 1: "Fag."