Since "no first-person" inevitably results in bad writing (an overabundance of passive voice; the use of "one" or "student" instead of "I"), I always tell my students, "You may use first-person in my class. In other classes, check with the instructor."
I never thought much about WHY teachers were telling students this. I vaguely remember someone telling me not to use first-person, and I vaguely remember ignoring that someone; other than that, it didn't seem like an important issue.
However, I recently discovered at least one reason teachers ban first-person: prevented from using first-person, students will set aside me-centered thinking and use credible evidence; that is, rather than saying, "I think this, thus it is true," students will write, "According to expert X . . ."
I don't buy this argument; in fact, I think banning first-person usage ends up doing more damage than good. If the problem is the lack of expert/credible sources in students' writing, not using first-person doesn't solve the problem; it just covers it up. After all, a first-person's account could be more credible than an "expert's" account. I'd much rather read a student's personal/eyewitness account of 9/11 than a thousand third-person conspiracy theories.
Associating first-person with subjectivity and therefore, with poor evidence also leads to a logical fallacy:
Since first-person produces less credible/more subjective/more me-centered evidence, then non-first-person must produce more credible/more objective/less me-centered evidence.Oh, yeah.
There's a lot of ridiculous non-first-person evidence out there which has no more credibility than a teenage driver claiming, "I never speed." A claim, introduced with an "I" or not, is still a claim, and any claim is disputable (as is all evidence).
I've seen the results of this logical fallacy in my students' writing; they confuse claims with support, thinking any statement without "I" is evidence (there's a huge difference between arguing, "Cats make great pets" and proving that cats make great pets). They also confuse claims with facts, thinking any statement without "I" is a fact: The United States is having a recession. Newsweek says so. I can use this in my paper!
All evidence/claims are testable, both personal evidence ("I experienced") and non-personal evidence. Determining credible evidence has nothing to do with first-person and everything to do with the credibility of the speaker/researcher/study/source.
In a well-intention desire to prevent excessive grandstanding, teachers who ban first-person are confusing cause with effect. A superfluity of "I think that . . ." "I believe that . . ." "I must be right because . . ." may be the result of a me-centered culture (and can get annoying), but it has little to nothing to do with whether the speaker can actually be trusted or whether the speaker's evidence is meritorious. I often tell my students, "Personal evidence is the strongest evidence you have; it just isn't enough except to your parents and your friends." But to say that personal evidence carries no weight at all is such an obvious untruth that students are liable to follow the teacher's instructions while missing the point. The result is terrible critical thinkers and even worse skeptics (exchanging one mass of information--my own--for someone else's mass of information doesn't lend itself to objective reasoning).
By excising personal experience as credible evidence, students will not only not learn about evidence, they will also (bizarrely enough) learn that rules of evidence don't apply to them. Personal evidence can be judged against a rubric as much as any kind of evidence; by divorcing personal evidence from the quest for credibility, the students' "me-centeredness" has been enforced. Hence my master's program--where a fellow student told me that all literature before 1970 is worthless because it's patriarchal, that the student's own warm and fuzzy feelings were of more objective worth than said texts, and that, furthermore, some political theoretician agreed with the student, all without the introduction of "I". Not that "I" would make it better; stupidity is still stupidity.
I don't think "me-centered" arguments in the college environment will go away until* students are forced to be intelligent (but not cynical) about information. We live in a media-saturated culture. This is good! Dismissing the not-so-great parts of that media saturation (Facebook, blogs--hee hee--the focus on the self) doesn't help anybody. Helping students recognize and assess it might.
*I don't think they will ever go away actually--college students have been "all about me" since Parisian college students in the 1300s used form letters to write home for money. Really. I'm not making that up.