Quote from the Professor in question: "I don’t consider him a Columbia student. I have no idea what he did on the Columbia campus. No one knows him."
Let's dissect this, shall we?
He says: "I don’t consider him a Columbia student."
OK, and? I don't consider tomatoes a fruit either - but they are one.
Then he says: " I have no idea what he did on the Columbia campus."
I have no idea what the vast majority of students at my campus do or did. Shit, I have little to no idea about what the students in my own classes do on the campus outside of my class.
And he clsoes with: "No one knows him."
Really? No one? He spoke to everyone on the campus and no one knows him? That's a bit of a stretch, but in the interest of collegiality, let's give the Professor the benefit of the doubt and assume that he did, indeed, poll everyone at the campus. The question then becomes when did he do his poll? Obama claims to have been at Columbia in the early 80's, so let's use use 1985 as a cutoff. That's thirty years years ago.
I'd expect that no student presently at Columbia would have been at Columbia in the early '80s to have a chance to meet Barack Obama; why bother going to a boring University when He-Man (or She-Ra) is on TV. So that's out.
So maybe he checked with other instructors. Certainly, it's plausible that an instructor could have been around for 30 years. But unless Obama attended their class, why would they know him? And even if he did attend, he was one person out of a sea of people. Class sizes are larger these days, but I've over the last 5 years, I've taught "Calculus I" every year, and the average class size is 87 students - and that's at the end of the course; it starts out at about 95 to 100 and that's per semester! If someone can commit to memory a roster of 50+ students and recall it 30 years later, well... hats off to them.
To make a long story short, I'm not convinced. It's unrealistic to suggest that Obama didn't graduate from Columbia. If he didn't, how did he manage to get into Harvard Law, which requires an undergraduate degree? Or did Harvard just not bother checking that the prerequisites for admission were met and verifying the transcripts that Obama would have had to supply by contacting Columbia's registrar?
And why would Obama fabricate so transparent a lie to begin with?