Really Mixed Conditionals

[tetyanaroi]

If he is such a good doctor, he will diagnose the illness.
I'm inclined to think that the either option is correct

[Dave Skypelessons]

I've just voted for 'he should have diagnosed the illness' - but I must admit, that is the FIRST time I have ever noticed that first and third conditional can be mixed in one sentence. And for that reason, every brain cell seems to be screaming 'it cant work', but Im sure its right!

[Tdol]

It has slipped under the radar of many grammar books, but it exists. It was a learner who alerted me to the form many years ago. It exists and works.

[Dave Skypelessons]

And thanks for bringing it to my attention! It's a very interesting conditional indeed.

Like I said - we just got off on the wrong foot