I just ran a sentence on, and it felt so right! I’ve never done it before and now I’m wondering what I’ve missed out on all these years.
Consider a sentence of the type:
If you find it has a white stripe above the spectrum, then it is not a black duck; it’s a mallard.
You’ll see here I’ve used a semi-colon. I would think this would be the widely accepted option.
Another acceptable option would be to start a new sentence, of course.
If you find it has a white stripe above the spectrum, then it is not a black duck. It’s a mallard.
Subtle difference of emphasis between these options but no doubt they will be passing the same factual information to the reader.
Somehow neither of these options quite capture the flow of this sentence (or these sentences). In my head, the final clause here has a more direct logical connection to the previous clause. They are a pair. The THEN points to two separate yet twinned resultant facts with equal weight. I can’t think of a situation in which I would be more tempted to opt for the illegal comma than this one.
If you find it has a white stripe above the spectrum, then it is not a black duck, it’s a mallard.
How do you feel about all this?