(I'm not sure) how to capitalize this sentence

When a sentence begins with a parenthetical clause (uncommon, I'm sure), how should the following portion be capitalized? My thought is it would be either

(In my opinion, at least[,]) the play was terrible.

or

(In my opinion, at least[,]) The play was terrible.

Since "The play was terrible" is a complete sentence, and "In my opinion, at least" is a parenthetical attachment, should "the" be capitalized? Should a sentence even start with a parenthetical clause?

Additionally (I will remove this part from the question if it turns out to be too separate an issue), should the comma after "at least" be present? Were the sentence written to include the parenthetical statement, it would be included, but it seems very strange to me to end a parenthetical statement that way.

Solution 1:

Since the parenthesis is part of the sentence, and comes first, you should not capitalize the the since it is in the middle of the sentence:

(In my opinion, at least) the play was terrible.

This looks rather ghastly, though, so you shouldn't start a sentence with parentheses. Instead you could say:

The play was terrible (in my opinion, at least).

Also, it is bad form to end a parenthetical fragment with punctuation. The ending parenthesis takes care of any separation that the comma would otherwise be needed to indicate.

Solution 2:

Also, it is bad form to end a parenthetical fragment with punctuation. The ending parenthesis takes care of any separation that the comma would otherwise be needed to indicate.

I disagree. However, if it is a mid-sentence parenthetical fragment, an exclamation mark or question mark might be necessary. Furthermore, a comma is often required after a closed parentheses, which contradicts your assertion that "the ending parenthesis takes care of any separation that the comma would otherwise be needed to indicate."

Case in point:

John thought about removing his laptop from the car (in order to not give any would-be thieves a reason to break in), but he decided it wasn't worth the effort.

Solution 3:

(It seems pretty weird to me, but) I'm willing to accept for the sake of the argument that you might be able to get away with putting a parenthetical preamble at the beginning of a sentence if the sentence proper began with a proper noun or with the pronoun I, since in that case the sentence would retain the appearance of completeness if the parenthetical were cast aside.

But fundamentally the notion of leading with parentheses strikes me as sending a confusingly mixed signal to readers. What is the point of putting "in my opinion, at least" parenthetically, anyway? I imagine that it serves to acknowledge that the assertion made elsewhere in the sentence is merely the author's opinion—something that readers may well have figured out on their own—but to do it in a way that subordinates the enclosed acknowledgment to the open opinion. Then why would you put the segregated acknowledgment on klieglight display at the start of the sentence?

If you think that acknowledging the opinion-based nature of the assertion that constitutes the primary content of a sentence is front-of-the-sentence material, you should be willing to present that acknowledgment without parenthetical hedging. Conversely, if you feel strongly that the acknowledgment needs to be subordinated (within parentheses) to the assertion, the acknowledgment has no business occupying the front of the sentence and stealing the thunder from the assertion that follows it.

This at any rate is how I would argue the case against opening a sentence with a parenthetical to an author who thought that doing it would be a neat idea. I wouldn't get to the question of whether the first word after the opening parenthetical phrase should be capitalized because I would deny the logical validity of leading off a sentence with a parenthetical phrase in the first place. And of course, when you're deciding how to handle a logically invalid construction, you can proceed however you want, without fear of invalidating it thereby.