Hacker News Reader

You're right, thanks. English is not my mother tongue so I still fall for some language traps.

Well, particularly in a subthread on Strunk & White, one should write "...differ on only two points" or "...contest only two points."

It's not that we ONLY contest these points (we may also, e.g., state them or rephrase them). It's that we contest ONLY these two (and no others). See the antepenultimate example of Rule II.16, "Keep related words together."

Why does “I contend” feel awkward to you? It is more specific than “I differ” because that could also mean that the author physically differs, which is awkward, while “contend” is specifically used for disagreement on some topic? Does “I contend” maybe has a ring to it of being scholastic/pretentious? (Also non-native English, just curious)

I would comment to drop the preposition:

“…only contend two things”

I think the trouble in the phrase is that “contend” has an active sense to it whereas “on” creates a more passive tone. Your solution is to swap to a more passive phrasing, but the alternative is also available.