Antonym for contra?

In the bolded phrase below, is there an obviously Latin-derived word we can use to replace "following"? (Perhaps pro?)

But Millar presumed, following Hume and contra Montesquieu, that mores or “moral causes,” as opposed to physical causes such as climate, are responsible for characteristic differences in human population.

Edit: I take contra to mean against and following to mean for. I'm wondering if there's a Latin word that serves as the standard antonym for contra and which could replace following.

You certainly could replace "following" with a more classic antonym of contra, but I'm not sure why you would want to. The result would be much less idiomatic. I believe your interpretation of "following" to mean "pro" is a bit premature. The usage here most resembles this definition from M-W:

follow
verb- to walk or proceed along (as a road or course)

In this way, to "follow" an argument simply means to trace it's reasoning, taking it at face value. You can be completely opposed to an idea, and still use "following" where "pro" would not make sense. For example: "Following your reasoning, since the sun will go supernova in 20 billion years, there is absolutely no point in recycling this aluminum can! What a rubbish argument!"

According to M-W, the antonym of contra is pro, which, again, according to M-W means "on the affirmative side : in affirmation." I agree with @lumbrjak though that it's not clear why you would want to replace following with pro: "following Hume" doesn't mean the same thing as "pro Hume". Also, contra, when opposed to following, means something like not following, against the thinking of.

If you want to oppose a Latin word to contra and stick with following, you could use secundum? From Wiktinary:

secundum: according to

Your example:

But Millar presumed, secundum Hume and contra Montesquieu, that mores or “moral causes,” as opposed to physical causes such as climate, are responsible for characteristic differences in human population.

Another possibility is as per. From Lexico:

as per: In accordance with.

Your example:

But Millar presumed, as per Hume and contra Montesquieu, that mores or “moral causes,” as opposed to physical causes such as climate, are responsible for characteristic differences in human population.

As per is not Latin, but it sounds like it is. :-)