Use of "I", "we" and the passive voice in a scientific thesis [duplicate]

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Style Question: Use of “we” vs. “I” vs. passive voice in a dissertation

When the first person voice is used in scientific writing it is mostly used in the first person plural, as scientific papers almost always have more than one co-author, such as

We propose a new method to study cell differentiation in nematodes.

Often the "we" also includes the reader

We may see in Figure 4.2 that...

However, I am writing a thesis which means I am the only author and I even have to testify in writing that the work is my own and I did not receive any help other than from the indicated sources. Therefore it seems I should use "I", but this seems to be very unusual in scientific writing and even discouraged as one may sound pretentious or self-absorbed. However, the alternative is to use the passive voice, which seems to be even more discouraged as it produces hard to read writing and indeed an entire thesis in the passive voice may be indigestible for any reader.

So far, I used the second form of "we" extensively that includes me and the reader. This form is often natural when describing mathematical derivations as the truth is objective and it suggests that I am taking the reader by the hand and walking her through the process. Still, I'm trying not do overdo this form.

However, eventually I will need to refer to methods that I propose and choices that I have made. Should I just follow scientific convention and use "we" although it is factually inaccurate or indeed write in the scorned-upon "I"?

I tried to use "I" in the first version of my thesis (in mathematics). When my advisor suggested corrections, the most detailed and strongly-worded of them was to use "we"; later, I asked another young professor whether one could use "I" and she said "Only if you want to sound like an arrogant bastard", and observed that only old people with established reputations can get away with it.

My extremely informal recollection of some articles that are more than, say, forty years old is that the singular is used more often, so what she says may be true but for a different reason than simple pride. The modern culture may disparage apparent displays of ego simply because of the greater prevalence of collaboration, whether or not your paper is a product of it. This is complete speculation, though.

I disagreed with the change at the time but acquiesced anyway, and now, with distance, I realize that it was a good idea. Scattering the paper with "I" draws attention to the author, and especially in mathematical writing, the prose is filled with impersonal subjects (that is, you often don't mean "I" literally, as in "If y = f(x), then we have an equation..."). Using "we" allows it to simply sink into the background, where it belongs. If it's your thesis, you don't have to put any special effort into reminding the reader who is talking, just like in an essay, they used to tell me not to say "in my opinion" before stating it.

EDIT: Oh, I forgot entirely about "the author". I hate that phrase, because it is just as inconsistent with "we" as with "I" and disingenuous to boot. If you have to make a truly personal remark, just say "I", and perhaps set off the entire comment by "Personally..." or something like that.

I don't think there's anything wrong with using we in single-author scientific journal papers. It's the tradition, and if you use I in scientific papers it stands out, not necessarily in a good way. On the other hand, a PhD thesis is not a scientific journal paper, but a PhD thesis, and if you want to use I in it I don't see anything wrong with that.

The passive voice should not be used to avoid writing I or we. If the entire thesis is written in the passive voice, it is much harder to read, and the sentences within it¹ have to be reworded awkwardly so that some good transitions between the sentences within a paragraph are lost. On the other hand, if some sentences seem to require the passive voice, by all means those sentences should be written in the passive voice. But the passive voice should only be used where it is justified, that is, where its use improves readability of the thesis.

¹ See how much better your sentences would read here.

By all means write "I". By an amusing coincidence, I have in front of me the article Deformations of Symmetric Products, a proceedings article published by Princeton University Press. The author is the late George R. Kempf, a distinguished algebraic geometer, and on the very first page I read [not we read:-)]: "My proof uses heavily the deformation theory..." . And on the second page "I will use without particular references standard facts from deformation theory". I could give any number of examples: this usage is quite widespread.