[Steven D]

Originally Posted by MrPedantic

We agree on #1: zero conditional.

To recap on other points of agreement: a zero conditional

a) requires a present tense in each clause;
b) can take 'when' instead of 'if';
c) presents a 'universal law'; or, by extension, what the speaker believes to be a 'universal law'.

Usually, with a zero conditional, you would expect the IF clause to contain the condition (the cause), and the main clause to contain the result (the effect). However, we've also suggested that although #2 presents the effect (lateness) before the cause (being stuck in traffic), #2 may also be regarded as a variety of zero conditional: 'if P, it's because Q'.

On the other hand, you don't accept #3 as a zero conditional. This I find interesting. #3 meets requirements b) and c); moreover, it presents the cause before the effect, in the way of a regular conditional. It's true that the tense of the IF clause is the present perfect; but some grammatical sources (Collins Cobuild, for instance) accept a present perfect in a zero conditional.

What kind of conditional is #3, in your opinion?

MrP

3. If a large vessel has opened a way, it is easy for a small one to follow.

I can only answer that question with a question. What if a large vessel has never opened a way? Is this still true all the time? I would say it's true if and when it does open its way, not if it has opened its way.


What if it's true when it opens its way but has yet to open its way? It's a possibility.