WHETHER, pronoun or substitute. L. The sense seems to be what, or which of two, referring either to persons or to sentences.
1. Which of two.
Whether of them twain did the will of his father? Matthew 21/
Here whether is a substitute for one of two, and signifies which; which of the two; but in this sense it is obsolete.
2. Which of two alternatives, expressed by a sentence or the clause of a sentence, and followed by or. Resolve whether you will go or not; that is, you will go or not go; resolve which.
Note. IN the latter use, which is now most common, whether is called an adverb. This is a mistake. It is the same part of speech as in the former example. The only difference is that in the former example it represents or refers to a noun, and in the latter to a sentence or clause.