There was a guy walking down the street and...

There was a guy walking down the street and he bumped into an old
buddy, Steve. Mark (the first guy) and Steve get talking and Mark asks Steve
what he's been up to.
"I'm going to university," says Steve.
"Oh, really. What are you taking?" asks Mark.
"Philosophy," he says.
"What kind of philosophy?"
"Logic, actually," says Steve.
"What's logic?" asks Mark.
"Well, it's kind of like this -- have you got a fishbowl, Mark?"
"Yeah, I do as a matter of fact."
"Well, if you've got a fish bowl, you probably like fish, don't you."
"Yeah, I do."
"And if you like fish, chances are you probably like animals, right?"
"Yeah, I love animals."
"Well, if you love animals, I'd say there was a probability that you
like people as well."
"Yeah, I do. I like people."
"And if you like people, I'll bet you like women."
"That's for sure!"
"And, Mark, if you like women I'd be willing to bet that you like sex."
"Geez, Steve, I love sex."
"Well that's the way it works, Mark -- that's logic."
"Wow, that's great," says Mark.
At the end of their conversation, Steve had to run and Mark continued
on his way down Richmond Street, only to bump into another friend, Paul.
They get talking and Mark tells Paul he ran into Steve only minutes
earlier.
"Oh, really. What's he up to these days?" asks Paul.
"He's at university," says Mark.
"What's he taking?" asks Paul.
"Logic," says Mark.
"What's logic?" asks Paul.
"Well, let me see -- it's sort of like this, Paul: Have you got a fish
bowl?"
"No, I haven't, Mark."
"What are you, some kind of fag?" says Mark indignantly.