Emphasis of this double negative? [closed]

Without which, we would be able to act at all.

I’m hearing this in my own head as, “Without which, we would not be able to act at all.”

So I'm wondering, is the former just a cleaner and less hectoring version of the second, with both meaning the same thing?

The reason you're hearing the written sentence in your mind's ear with a not in it is that
that way, the sentence is grammatical.

At all is a Negative Polarity Item, which means that it can't appear grammatically at all,
unless it's inside the scope of a negative trigger; and by far the simplest and most common
negative trigger (linguists would say the "default" or "unmarked" trigger) in English is not.

Without, which is a negative trigger, appears at the beginning of the sentence and doesn't command (and therefore can't trigger) at all, which is in a subordinate clause.

Thus, your brain obligingly supplied not for your mind's ear, because your brain knows English syntax, whether you do or not.