All clauses require a tensed verb.

Not in linguistic contexts, else the very phrase “non-finite clause” would be a contradiction in terms, as would be the phrase “absolute clause” (which, unsurprisingly, turns up more Google hits than “absolute phrase,” while “absolutive phrase” hardly turns up any at all).

A participle is not a verb; it is a nominative or adjective.

Source, please? Even if I weren’t ABD in Linguistics I’d have to call B.S. on that one. The notion that being is not a verb seems counterintuitive, at best. The notion that no non-finite verbs do, including infinitives (about as “non-finite” as they get, by definition) doesn’t pass the laugh test.

All clauses must have at least an implied subject and a tensed verb. All.

Correction: all finite clauses must have a finite verb, but all that is required of clauses in general – finite or nonfinite – is that they contain both a subject (noun phrase) and a predicate (verb phrase). Tense is irrelevant.

“Going to the store yesterday” is a phrase, not a clause.

Indeed, but not for the reason you suggest. The reason it’s only a phrase (or, more specifically, a verb phrase) is because it lacks a subject. Tense is irrelevant; “went to the store yesterday” isn’t a clause, either, and for the same reason.

“Going to the store yesterday, we saw John.”

“Going to the store yesterday” is a phrase, not a clause. “We saw John” is a clause. The only difference between a dependent and independent clause is that a dependent clause requires an independent clause. Both require tensed verbs.

“If I were not a linguist, I might not know this.”

Both are clauses. The first clause is dependent; the second is independent.

The children [being] in bed, we stayed up and watched crappy SNL reruns

Also, be careful not to confuse the terminology. The term is “absolute,” not “absolutive.” The latter refers to an unrelated concept, namely that some languages, dubbed ergative-absolutive, group objects of transitive verbs together with subjects of intransitive ones, while accusative languages (like English) treat the subjects of both as largely the same, and objects as distinct. It’s an interesting issue, but wholly unrelated to the controversy surrounding the militia clause (or, for that matter, the English language).

Sign me your friendly linguist reader.

IF they wanted to say that the states had rights to militias, they would have said something like: “Congress shall pass no law abridging the rights of states to form militias.”

No, they wanted to say “An armed citizenry is the sole defense of a free government, therefore the right of the people to keep and bear arms shall not be infringed.” Then they hedged a bit so that the states would have some control over the collected citizens, known then as “the militia”, assuming they weren’t busy overthrowing the state.

Since the article XRLQ linked to talked about the “absolute” I’ll only address that in regards to grammar…

Some of the sources I used (because electronic versions are available or I have an actual hard copy):

A Dictionary of the English Language by Samuel Johnson, 15 Apr 1755

An American Dictionary of the English Language Exhibiting the Origin, Orthography, Pronunciation, and Definitions of Words, By Noah Webster, LLD, 1828

McGuffey’s Eclectic Primer, Revised Edition, 1800-1873

Rudiments of English Grammar, Noah Webster, 1790

There have been very few actual grammar changes in the English language as used in the United States in the last two hundred years–none are major changes. That’s why anyone with only a little education can read the wittings of that era. There have been no changes in the definition of an absolute (nominative absolute).

In Rudiments, Webster defined the nominative in rule XV.

[begin excerpt]

A nominative case or word, joined with a participle, often stands independently of the sentence. This is called, the case absolute.

Examples. The sun being risen, it will be warm. They all consenting, the vote was passed. “Jesus conveyed himself away, a multitude being in that place.”

Explanation. The words in italics are not connected with the other part of the sentence, either by agreement or government; they are therefore in the case absolute, which, in English, is always the nominative.

[long "s" changed to regular "s" in all cases, ed.]
[end excerpt]

The founders had available to them Samuel Johnson’s famous dictionary and Webster’s grammar book.

Granted that I’m not an English grammarian by profession, let’s examine the Second Amendment from a grammatical standpoint.

So that we know exactly what we’re examining, here’s the text of the Second Amendment, as passed by Congress and ratified by the States: “A well regulated militia being necessary to the security of a free State, the right of the People to keep and bear arms shall not be infringed.”

There are only a couple types of sentences: Simple, Complex, Compound [there are two special cases of Compound called Compound-Complex]{1}.

A *simple sentence*, also called an independent clause, contains a subject and a verb, and it expresses a complete thought.

The Second Amendment is not a “simple sentence”–it contains two clauses.

A *complex sentence* has an independent clause joined by one or more dependent clauses.

Hmmm… looks like that could be it, but before we make the final call, let’s continue looking at the other types of sentences.

A *compound sentence* contains two independent clauses joined by a coordinator. The coordinators are as follows: for, and, nor, but, or, yet, so. Except for very short sentences, coordinators are always preceded by a comma.

Nope, doesn’t fit. Let’s examine compound-complex sentences next…

There are two special types of compound sentences. First, rather than joining two simple sentences together, a coordinating conjunction sometimes joins two complex sentences, or one simple sentence and one complex sentence. In eihter case, the sentence is called a *compound-complex* sentence.

Has to have more than one independent clause–that one doesn’t fit. Continuing on…

The second special case involves punctuation. It is possible to join two originally separate sentences into a compound sentence using a semicolon instead of a coordinating conjunction. Usually, a conjunctive adverb like “however” or “consequently” will appear near the beginning of the second part, but it is not required. Also note, in modern English, an em dash (–), which indicates a sudden break in thought–a parenthetical statement like this one–may sometimes be used in place of a semicolon.

Again, it has to have more than one independent clause, and again, the definition doesn’t fit.

The only sentence type that fits the sentence that is the Second Amendment is a “complex” sentence. One independent clause and one or more dependent clauses. Lets now examine the text of the Second Amendment and ensure that is factually correct–that it has only one independent clause and the other clause is a dependent clause.

When looking at the Second Amendment, the phrase beginning with “a well-regulated militia” and ending with “a free State” is an absolute phrase, a.k.a. nominative absolute{2}. A nominative absolute consists of a substantive–a noun or noun substitute–and a participle and has no grammatical connection with the rest of the sentence. The phrase is not an independent clause–a group of related words that makes a complete statement–and does not stand on it’s own. It is a dependent clause.

The phrase beginning with “the right of the people” and ending with “shall not be infringed” is an independent clause and is not grammatically dependent on the preceding nominative absolute phrase in any way. By itself this phrase fulfills the definition of a “simple sentence” above. Again, it is an independent clause.

Yep, the Second Amendment has one independent clause and one dependent clause, the dependent clause being a nominative absolute.

Now that we’ve carefully examined the Second Amendment–as distributed to the states and then ratified by them–and using the definitions above we can see that the Second Amendment is in fact a “complex” sentence. It has one dependent clause and one independent clause.

Here it is again, just to ensure we’re all on the same page: “A well regulated militia being necessary to the security of a free State, the right of the People to keep and bear arms shall not be infringed.”

We can see that “the right of the People to keep and bear arms” is not dependent on the “well regulated militia”; however, the “well regulated militia” is dependent on the right of the people [remember which words were in which clause--dependent and independent--that's how you tell what is dependent on what].

The USSC has ruled that every word of the Constitution must be read as being necessary. If the right of the people is not dependent on the militia, then why are the words “well regulated militia” included in the Second Amendment? Those words give ONE of the reasons why the right of the People to keep and bear arms shall not be infringed. Those words also show WHAT type of arms should be specifically protected; the type necessary to a “well regulated militia”.

Now, continuing on, someone might ask, “Why would the framers only include that ONE [Militia] reason for protecting the right to keep and bear arms?” You must remember that the Constitution is a document setting up the framework for the Federal Government–a government that isn’t granted any power [Article 1, section 8] to interfere with the everyday concerns or uses of Arms by its citizens, such as hunting, target shooting, self-defense, etc. The only area of concern for the Federal Government in regards to arms are military uses–and thus the “militia” reference.

The right of the people to keep and bear arms is protected at the Federal level so that there is a pool of already armed citizens that may be called upon to “execute the Laws of the Union, suppress Insurrections and repel Invasions” [those are the only uses of armed Citizens as a militia the Constitution authorizes Congress or the President].

1. The Structure of a Sentence
http://www.arts.uottawa.ca/writcent/hypergrammar/sntstrct.html
http://eslbee.com/sentences.htm

2. Nominative Absolute
http://englishplus.com/grammar/00000390.htm

Also see:
Sentence Diagrams
by Eugene R. Moutoux
~ One Way of Learning English Grammar ~
Sentences from the United States Constitution
Amendment 2:
http://www.geocities.com/gene_moutoux/diagramamend2.htm