How to decide whether I should use “we” in an essay? The answers to this question promote a view that the personal pronoun we is acceptable in an academic paper. But I did not see an answer there, or more generally on this site, that discourages the use of we. This question is different to the one mentioned above because it queries whether the word we should be used at all, not just to ask whether I or we is more appropriate. 

The economics department at my university (UCT) discourages the use of personal pronouns in an essay – I was marked down in my essay for my use of the word we. At the end of my essay, I wrote 


  In conclusion, we note that the European sovereign debt crisis created uncertainty in the global financial market, and South Africa was one of many countries that dealt with this. 


I decided to use we in my essay because I had grown accustomed to seeing it in mathematics textbooks, so I assumed that it was formal enough. But the economics department says that it is not formal enough. 

Even though it seems acceptable to use we in some circles, it seems that it is a point of debate. What guidelines should I be using in order to make my decision about whether to use we or not?* Should I continue to use we as I see fit, except for economics essays? Or, should I apply this rule to all my academic essays (I also study public policy &amp; administration)?

It would ostensibly be silly to have different writing styles emanating from the same person. The problem has not been brought up before, and I have used the word in a number of sociology essays in first year, and one public policy &amp; administration essay in second year. In those essays, I used the word in the following ways.


  In this section, we discuss motivations for why provincial government should be restructured. 


and 


  Applying this model to provincial government, we can graph a U-shaped function of long-run average cost.


and


  Approaching the question from the side of the teacher, we find that inequality can be caused via culturally insensitive teaching methods.


As a final clarification, I do prefer to use the word.

* Edit: Although it was not initially made clear, I have not been provided with style guides. However, I doubt that I would ask this question if I were provided with style guides. Saying that I should "follow the style guide" makes perfect sense, but doesn't really help me in my situation. I asked this question on academia.SE so that I could ask others to brainstorm ideas about how I could make the decision without a style guide (e.g. how were those rules formed in the first place?).
You're doing a postgraduate degree, so you should have been taught / be about to be taught the basics of academic writing.

Here is one of the basic rules.


Follow the style guide.


You've been told what the style guide for your coursework says about personal pronouns: it says don't use them. Follow it. Don't use personal pronouns in your coursework.

When you write for something with a different style guide, follow that style guide instead.

Different style guides have different rules. That's what makes them different.

No, it is not ostensibly silly to have different writing styles from the same person, assuming that person can comprehend and follow Rule 1, above.