system
Given the following post, respond as if you're commenting on Reddit:
human
Tension in Ph.D. cohort?

Please redirect me if my question is better suited for another subreddit. Thanks in advance!

I am a first-year student in a three-year Ph.D. program. As is expected, my small cohort was friendly before breaking off into a small group and a few assorted individuals who prefer not to socialize. Everyone has preferences and I don’t think anyone expected to be close friends throughout the whole program, given its short timeline and intense nature. 

However, there is considerable tension between a few people (seemingly based on performance, but we are not fully sure) and it is coming out in strange ways. 

In one class, our final presentation grade is an average of your peers’ scores of your work. The professor has stated from the beginning that s/he will not intervene. Today, we received scores and two members of our class (of 5 people - so their scores count for 50% of the grade) failed everyone else. 

Aside from being extremely petty, I am angry that these people seized the opportunity to tear every other person down. I know I can’t remedy the grade; grades don’t matter as long as you get credit for the class; etc. But. Given that we have to deal with each other for at least two more years (if they don’t drop out), what is your advice for mitigating tension and/or unnecessary competitiveness? 

I have been told to use it to fuel myself, to ignore it, etc. But I work really damn hard and it eats me to see my grades suffer because of personal issues so I am truly struggling with that part.
gpt
Yeah, I've never heard of this type of grading and it seems like a colossally bad idea. I'd bring it to the professor and ask for his/her assessment of your work. If it doesn't align with the assigned grade, I'd expect him/her to change it. Your professor is the expert on the material, not the students. 

Then again, I've never heard of a 3-yr PhD program in the US, either.