Why does “a comma” exist between “to+infinitive clause” and “a relative clause” in this sentence?

Question

In the link https://www.archives.gov/founding-docs/declaration-transcript, it is written

We hold these truths to be self-evident , that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

To catch your attention, I made the first comma between "self-evident" and "that all men.." bold and would like to ask a question about it.

There is surely a list here consisting of "that-relative clauses(defining)" in a row and that's why there are commas. However, I can't understand why the first comma exists. Putting the first comma there means "to be self-evident" is the first item of the list, however, I'm pretty unsure if we can create a list consisting of both relative clauses and infinitive clauses.

I don't think that "to be self-evident" can be the first unit of the list because it is not something with the same type as relative clauses. If it can, well we should be able to change the place of "to be self-evident" and put it there as the third or fourth element of that list, which probably doesn't make sense and is ungrammatical.

Therefore, I suggest removing the first comma.

What do you think?

Answer 1

All relative clauses have a gap, ie. a missing element that is only semantically filled by the noun or noun phrase it modifies. For example, the direct objects of "bought" is missing in the sentence below, but it is semantically filled by "the car".

I like the car that you bought the car

Now, let's take a look at your sentence:

We hold these truths to be self-evident , that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

There are three that-clauses:

1. That all men are created equal
   
2. That they are endowed by their Creator with certain unalienable right
   
3. That among these are Life, Liberty and the pursuit of Happiness
   

All of these clauses form a complete clausal constituent: there are no missing subjects, objects, or complements. Therefore, they are not relative clauses; they are declarative content clauses.

A declarative content clause can be set off by a comma of it is intended to be supplementary (parenthetical), which I think is not the case here. So in my opinion, the first comma should be removed.