So I read other people's dissertations (in which they are the sole author, duh), and scholarly papers attributed to a single author, and they never use the pronoun "I". It's apparently verboten.

Most of the time they try to avoid using first person pronouns altogether. But when you're describing your experimental setup, for example, this logically leads to passive constructions like: "40 subjects were selected at random." or "Stimuli were chosen on the basis of emotional salience."

And we always learned that such passive constructions are weak, did we not? I quote from the Bible of style, Strunk and White:

The active voice is usually more direct and vigorous than the passive:

I shall always remember my first visit to Boston.

This is much better than:

My first visit to Boston will always be remembered by me.

The latter sentence is less direct, less bold, and less concise. If the writer tries to make it more concise by omitting "by me,":

My first visit to Boston will always be remembered,

it becomes indefinite: is it the writer, or some person undisclosed, or the world at large, that will always remember this visit?

This rule does not, of course, mean that the writer should entirely discard the passive voice, which is frequently convenient and sometimes necessary.

[snip]

The habitual use of the active voice, however, makes for forcible writing. This is true not only in narrative principally concerned with action, but in writing of any kind.

Exactly. And I've seen lots of advice for dissertation writing point directly to Strunk and White. But if we don't follow their advice, our dissertation is going to be riddled with passive constructions.

Even stranger is that I've occasionally seen the use of the first person plural in dissertations: "We found that the difference was statistically significant." We??? Do you have a frog in your pocket?

Here's essence of the contradiction: We are told that a dissertation is supposed to contribute something original and substantial to the body of human knowledge. It is not meant to be carried out cooperatively, but is to be the sole product of an individual, which contributes work and ideas that have not been seen before.

And yet we're not supposed to use the word "I". And there's something completely ludicrous in using the word "we" on a document that is supposed to be, by its nature, an individual enterprise.

If it's meant to purge the ego from the enterprise, I could possibly understand that as motivation. Or to highlight the contributions of all those researchers that have come before...the "standing on the shoulders of giants" ethos.

But if dissertations are so heavily dependent on the bedrock of work laid down by previous researchers, and it is such a cooperative enterprise, then why stress that it needs to be such an original, individualistic endeavor?

It's almost as if they're implicitly saying, "Come up with something incredibly original, but whatever you do, don't take individual credit for it!" Hell, you can't even say, "I cleaned the rat cages by myself."

It's enough to make a person (a vague, unidentified, numberless person) schizophrenic.