Does "before" make the Perfect Tense redundant?

(Sorry for bothering you again with the Perfect Tense, I hope it ends soon.) I took a quiz and a grammar website said that I made a mistake.

Right sentence:

When I showed up to take a look around, there were at least twenty other people who had arrived before me.

My sentence:

When I showed up to take a look around, there were at least twenty other people who arrived before me.

In the second clause I used just arrived because I thought that the word before does all the job. Is it a real mistake? What sentence does sound better? Does “before” make the Perfect Tense redundant?

Answer

You are right that before with the past perfect makes it somewhat redundant. However, using the past perfect is the correct version of the sentence. The sentence is narrating the past and needs to describe a prior event, the exact purpose of the past perfect tense.

As StoneyB pointed out, the key to realizing that the past perfect is needed here is the when clause. The phrase when I showed up specifies a reference time in the past. In order to then talk about something which happened prior to that reference time the past perfect tense is necessary.

And about the redundancy, time adverbials (such as before) with past perfect can make it slightly redundant, but in a clarifying way. It's similar to specifying "positive 2" instead of just "2" as an answer on a math test, it becomes slightly redundant, but is more specific and clear.

So in summary, past perfect + time adverbial is a slightly redundant, but completely correct, grammar construction. And generally speaking, past simple + time adverbial is not a sufficient replacement for the past perfect tense.