Need clarification on the use of than and then

Question

In the sentence "If you think that post is coherent, than you are either drinking or need help". One person says a comparison is being made. As such, the rules for than/then apply and the word "than" is correct. Another person says it's a conditional statement. As such, the rules for if/then apply and the word "then" is correct. Which person is correct?

Answer 1

It should be the second case----"if / then".

The only part that could be interpreted as a comparison is the last phrase, but even that is not really a comparison. Comparisons typically involve the use of an adjective such as "taller", "wider", "warmer"...etc.

Consider this: "IF" is always conditional----with or without "THEN".

Answer 2

That may sound like a comparison because of the analogy used. Grammarly speaking, that is not a true comparison. Therefore your use of "then" instead of "than" is correct.

Answer 3

The comma is a clue! If/then constructions require it (e.g., If you bring an umbrella, then it won't rain), but I can't think of an instance when a phrase following a comma could start with "than." It's function is to compare, so it must sit between the two subjects of the comparison (e.g., Jan is older than Marcia).