Is the past tense correct in "Did you know Fred was a doctor?" [duplicate]

Question

Possible Duplicates:
He didn't know where New Jersey was…
Tense change: previous actions on something that's currently true

My wife and I were disagreeing about this today:

1. Did you know Fred was a doctor?
2. Did you know Fred is a doctor?

I was arguing for (1) based on what seemed to "sound right." My wife claimed that, since Fred is currently alive and still practicing medicine, present tense should be used. However, we agreed that the negation of these sentences uses was:

I didn't know Fred was a doctor.

Here I think everyone would agree that is would sound wrong!

So which is correct between (1) and (2)? And why? Is this some kind of subjunctive?

Answer 1

My vote for "is" in both cases, negated or not. If you have the qualification, then you are a doctor.

Compare

Did you know that Fred is a doctor? - Oh, is he? I'd never have guessed.

with

Did you know that Bob was a fighter pilot in the war? - Oh, was he? I'd never have guessed.

Answer 2

Tense use isn't dependent solely on current "real world" time: among other things, it also reflects some other time 'reference point' of events, which can arbitrarily be in the past or future relative to the time of speaking.

And so, the sentence "Did you know Fred was a doctor?" does not necessarily make any reference to whether Fred is currently a doctor in terms of "real world" time, but rather whether they were at the time reference point of the "knowing". Whether or not they currently are a doctor at the time of speaking is irrelevant: that isn't the point of time being referred to.