Correct usage of “so would” and “a priori”

Question

Is this phrase syntactically correct?

Because X may take different forms, a priori so would Y.

I am especially asking about the usage of "so would", but also about the place of "a priori".

Maybe it is better to say

Because X may take different forms, a priori it would be the same for Y.

Answer 1

Both sentences in your question are correct and they mean the same thing. The syntax is different.

Because X may take different forms, a priori so would Y.

There's nothing ungrammatical about a priori here. It's functioning as an adverb meaning "based on theoretical deduction". As for so would Y, it is a construct used to express agreement with what has been mentioned before in the sentence. In a dialogue where you can have exactly the same construct it would sound more natural:

A: "I would definitely choose the red shirt over the yellow one."

B: "So would I."

When so is placed in the beginning of a sentence or a clause to express agreement, there is inversion between the auxiliary verb and the subject, in other words you write the subject-auxiliary verb in question form. The main verb is omitted. This is a shorter way of saying I would do the same thing.