Emphasis on the DO

In English, we have something called the emphatic tense of verbs. It is sometimes known as the periphrastic tense because it seems to be an extraneous usage of verbs, but in Modern English, it is paramount because it is usually how we negate our present and past tense verbs and it is also how we pose questions.

The emphatic tense is constructed in this way:

Subjective Pronoun + Conjugated "to do" + bare infinitive

Example: He does have

The emphatic tense is especially important when it is being used in questions such as the one below:

Example: Do you have the time?

One would probably answer, "Yes, I have the time", but he could easily just say, "Yes, I do". Here, the periphrastic use is very important because it makes the verb, "to do" very versatile, and its versatility is crucial to the syntax of a sentence.

In older forms of English, before "to do" was ever used as a form of auxiliary verb, questions were posed by inverting the subject and verb. In French, this is still one way questions are formed, but in Modern English, it is almost nonexistent. Nowadays, this is really only seen in some fixed expressions such as the ones below:

Example: What say you? (What do you say?)

Example: Where go you? (Where do you go?)

Example: What have you? (What do you have?)

Then there is the use of negating sentences by using a conjugated form of "to do" plus a "not" that supervenes. This is almost exclusively how a person would negate a present or past indicative clause in Modern English that doesn't have the verb "to be" as its negated verb or the use of "to have" as a construction of a perfect tense such as "have spoken". For example:

Example: I do not see him.

Theoretically, one could say it in its passé form, "I see not him", wherein one can see that the adverb "not" supervenes the main verb of the clause, but this is very much an archaic or humorous construction. Although this might be considered archaic, there are some fixed expressions that use this form:

Example: I know not what you are talking about.

Whatever the case may be, "to do" is usually used to negate indicative mood sentences. In subjunctive cases, it is very rare. It's usually seen in only past subjunctive cases such as the one below:

Example: If you did not want to go to Florida, you could choose Alaska.

Normally, this is all right provided it be talking about something hypothetical that hasn't already occurred. I state this because, if it were a subjunctive mood statement that is hypothetical about something in the past, it would have to be in a Past Perfect Subjunctive construction:

Example: If you had not wanted to go to Florida, you could have chosen Alaska.

Now, for the present emphatic subjunctive, I suggest that one avoid this as much as possible, especially in third person singular because it is considered by many to sound unintelligent. A normal, everyday present emphatic subjunctive construction would look like this, but most people do not consider it to be subjunctive because they never conjugate it as a subjunctive in third person singular:

Example: If you do not come to school, you will not pass.

If this were third person singular, one would probably say "does not", and those who say "do not" would be frowned upon as being uneducated, even though it technically would work as "do not" because the protasis here is technically subjunctive in its most prescriptive, semiotic form.

While this may be true, most people do not treat it as such so a construction such as "if he do not" should be avoided and in place, one should say "if he should not" or "if he not". Again, though, to each his own I always say. I'm not here to rip apart spoken English; merely I want to do a semiotic study of it, especially as it appertains to semantics. Here's an example that I had used in my last article on the subjunctive mood:

Example: If he do bleed, / I'll gild the faces of the grooms withal, for it must seem their guilt. (Macbeth, Act 2, Scene 2, Lines 71-72)

This should really be left for Shakespeare. I'm not in the mood to get into the semantics of this, but one should try to avoid a present emphatic subjunctive construction in all persons I say. This is only important when writing formal papers. I could care less how you might say it somewhere else. There are parts of the subjunctive mood that have a place in modern English, and there are parts that have no business being around anymore.

That's the great thing about English; it's very versatile—one could use the indicative or subjunctive in many places and they both can be correct. An example would be, "You should shut up before you be fired" compared to saying "you are fired". This is an older form of the subjunctive mood, and in my mind, it can be both, even in formal writing. The important present tense subjunctive construction is only after "that clauses" and for its past subjunctive, it's only necessary whenever "to be" might rear its ugly face.