Order of placing clauses in a two-clause sentence

Question

Which of the following is correct:

1. If you so desire, you may download the content.
2. You may download the content, if you so desire.

Apparently, they appear to be all same but, on critically examining the sentences, I find an issue with the first sentence. The issue is: the first clause in the sentence refers to a desire by using the words If you so desire, though the desire has not been expressed by then; the desire has been expressed in the subsequent clause; so, going logically, it is the second clause - that is, you may download the content - which should come first and, it is only after the desire expressed in second clause has been mentioned, the first clause - that is, If you so desire - should come.

The second sentence follows this order, so it is only the second sentence which appears correct to me. Am I correct?

Answer 1

Yes, this "so" is an anaphor and it demands an antecedent.  Normally, an antecedent precedes the anaphor -- which is the reason we call it an antecedent.  However, there is a case when the so-called antecedent follows the anaphor in sentence structure.  Your first example is a good example of that case. 

The "so" appears in a subordinate clause.  It's antecedent appears in the main clause. 

The subordinate nature of "if you so desire" sets up the expectation that a main clause -- a clause that comes before it in importance if not in word order -- will contain the antecedent.  In the main clause of your examples, "[to] download the content" is the nature of the desire.  That is the antecedent of "so". 

We could paraphrase the example by including the antecedent in the subordinate clause and leaving the anaphor in the main clause, if the subordinate clause occurs first in the word order: 

If you desire to download the content, you may [do so]. 

The anaphor must come second.  It can be second in word order or second in clause importance,  but it must be at least one of those.  The anaphor fails if it comes first in both those considerations: 

You may [do so] if you desire to download the content. 

In this sentence, the "[to] do so" (or even just the bare "may") does not refer to "to download the content".  It has to refer to something else, most likely to something from the prior sentence. 

Both of your original examples are correct.  The first one is correct because the clause containing the anaphor is second in importance, and we know that a more important clause must follow and must contain the antecedent.  The second one is correct because the clause containing the anaphor is second in word order, and we know the antecedent of "so" before we reach the anaphor. 

The second example is easier to understand and easier to explain, but it is not more correct than the first.  Both examples are correct, both examples can be understood, and both examples can be explained. 

Answer 2

Both work. "So" doesn't imply that which just happened or was stated, it just refers to a proximate thing, in past or future, before or after. It's entirely equivalent in meaning to "if you would like", which also doesn't mind whether the paired phrase comes before or after.

Answer 3

Both sentences are equivalent and correct. Maybe the nuance can be shown by an example which has more than one choice:

"If you so desire, you may download, or print out, or email the content."

To me, a native speaker, when used this way, it indicates there is an anticipation of the different actions by the person spoken to (as you point out the desires are enumerated later). It is softer and more polite. The phrase itself carries a feeling of deference. For example, speaking to a friend, the equivalent might be:

"You could download, or print out, or email the content."

Putting if you so desire at the end, seems to say well, if that's what you want to do, more of a hedge by the speaker than anticipating and trying to fill a need of the person spoken to.