A great question: "If I was" vs. "If I were"

Over in the comments on the calendar site, Reader 13c11a (we don't have readers with uninteresting names) asked a great question:

In the piece below, which is correct--was or were--and why? Thank you very much.

He repeated that he would neither have the IV removed nor let me go. He went on to explain that he could not discharge me because I was in serious condition. I argued that I couldn’t have been lawfully admitted and that I was going to leave. He explained that he admitted me as an emergency and that I was far too ill to leave. I explained that I had two twenty year old cats at home who were expecting me to return on time to feed them. He was a broken record: he would not allow me to leave. I thought this strange because he was half my age. I don’t know why I thought that mattered. It was as though he was/were wearing a badge and I had been pulled over.

  I replied:

What a great question, and that is an engaging and interesting piece of creative prose! I commend you, 13c11a, if this is original to you.

Around here we don't like technical terms so much, so in keeping with  that I'll just say that any time you're talking about something that could never be true you use "If I were," as in "If I were you. . . . " Conversely, it's natural to say, "If I was off course, I wasn't aware of it at the time," because it's entirely possible that you might have been on or off course.

But then it gets slippery, especially since you can't always say it's one or the other. The song goes "If I were a rich man," which is fine. I get it. Tevye in Fiddler on the Roof isn't a rich man, so the statement is not true. But is there a context for "If I was a rich man"? How about "If was a rich man then, I certainly didn't feel it at the time"?

Or how about if Tevye had just plain sung it, "If I was a rich man," with all of his life circumstances just as they are? Would that be so wildly out of bounds? No, not really, because in modern usage the "were" is not required in every case that it could be used. I'd argue no one would bat an eye at "If I was a rich man, all day long I'd biddy biddy bum, if I was a wealthy man."  

Certainly in creative prose you can let your ear guide you somewhat. In my opinion, "It's as though he was" would read better than "It's as though he were" in your passage. I could even argue it is more correct because it strengthens the metaphor of nurse/cop and patient/suspect. That is, if you go with the idea that "If I were" is for cases that are impossible and "If I was" is for cases that may or may not have been possible in the past, you can nudge your metaphor toward the latter interpretation and make the poetic declaration of "He was a cop, and I was his suspect" simply by choosing "was" over "were."

If you do want the technical term, you call this the subjunctive mood, and a good discussion of the point is on the English Language & Usage site.