Since the topic is making the rounds in the blogsphere (Kieran Healy here; CalPundit here; Invisible Adjunct here; Yglesias here), I’ll toss in my two cents. Cent one: there are a lot of genuinely funny stories going around about students suddenly elevating their prose to Dostoyevskian levels, or their mathematical analysis to the level of Nash. The implication is that plagiarizers are all stupid and sure to get caught by clever professors.
Here’s my story. I had a student whose previous short paper was on internet shopping, and a shallow treatment at that. Internet shopping was actually a fine topic, given that the course was on the Economics of Innovation–shopping on the web was, at the time, indeed an innovation. The final paper that the student submitted, only a few paragraphs into it, went into text along the lines of “Let N denote the number of firms, and assume that there is a mass of consumers of [Lebesgue] measure one.” Later, the paper referenced Subgame Perfect Nash Equilibria and the like. Clearly, it was plagiarized. I gave the student an F, after threatening going to the dean and pursuing expulsion.
Cent two: It’s always important to think about sample selection. As professors, we only observe the bad plagiarizers. There are likely rather clever (but presumably lazy) students who are skilled plagiarizers. When plagiarism is done well, professors don’t know that it’s occuring. So the various amusing stories are not representative of the average instance of plagiarism, but simply a random sampling from poorly executed plagiarism.
Yes, plagiarism is very bad, and I do not think expulsion is too severe a punishment for plagiarism. For a handful of students, college and knowledge are intrinsically exciting; for such students, grades are probably not even necessary. For the remainder, the degree and the transcript are certificates indicating the student’s capability for learning. (So the cynical, but on balance true, answer to the eternal question, “when and how will I use this in real life?” is “Never. But if you can figure this material out, you can figure out other complicated things. Getting an A in my class will be credible evidence of your ability to do so”).
In addition to being stealing, plagiarism adds noise to this signal, benefitting poor but unethical students at the expense of hardworking and/or brilliant students. My advice to students is “don’t do it”, because if you are dumb enough to need to do it, then you probably won’t get away with it. My tip to faculty is that you aren’t catching as much of it as you think you are.