The word “if” is often mistakenly used as a substitute for the word “whether.” In the olden days, say, before the twelfth century, “whether” used to mean “which of the two.” Whether is always used after prepositions and before infinitives.
There was a big discussion about whether to complete the well at all. (after preposition)
They can’t decide whether to complete the well with an ESP or PCP. (before infinitive)
Both “if” and “whether” can be used in front of a clause that contains a subject and verb.
I don’t know if that kind of well can be completed at all.
I don’t know whether that kind of well can be completed at all.
How shall we remember this?
Use “if” to express a condition.
Example: We’re going to complete this well with an ESP if it produces any water.
Use “whether” to express alternatives. (Note: sometimes the “or not” option is implied.)
We’re going to complete this well with an ESP whether it produces water or not.
I’m not sure whether we’ll have time. (or not)
Funny Poem of the Day: (note the subjunctive verb tense)
Whether the weather be cold,
Or whether the weather be hot,
Whatever the weather
We’ll weather the weather,
Whether we like it or not.