How should I understand this usage of "for"

Question

This latter fact could not simply be a conjunctive fact, combining a finite number of facts about the whiteness of each individual swan. For even if a is white, and b is white, and c is white, and so on, for each individual swan, a, b, c, etc., it does not follow that all swans are white unless we are also given that a, b, c, etc. are all the swans there are; and this itself is a general fact. <Lowe, E. J., 2008, "Metaphysics", in The Routledge Companion to Twentieth Century Philosophy, p. 445>

Friendship, for example, is valuable in this way. For while friendship is undoubtedly useful, and therefore of instrumental value, one would be missing out on something important if one didn’t appreciate the fact that having friends is good for its own sake. Indeed, someone who only values their friends because it serves their wider interests arguably doesn’t have any real friends. <Pritchard, D., 2018, What is this thing called knowledge?, p. 10>

I have trouble comprehending these "for" in bold. I think these are conjunctions. However, as far as I know, unlike "because", "for" as a conjunction is not placed at the beginning of a sentence. How should I get it?

Answer 1

Yes, "for" would usually be considered a coordinating conjunction in your examples. (It is one of the so-called "FANBOYS" coordinating conjunctions.)

As you note, many sources (especially more traditional ones) recommend that you not place a FANBOYS conjunction at the beginning of a sentence. Nevertheless, it is very common for English writers to begin sentences with those conjunctions, and many grammarians (I believe the great majority, though I don't have any statistics) consider doing so to be perfectly acceptable. That is what the authors have done in your examples.

When "because" is used as a conjunction, it is used only as a subordinator (never as a coordinator), so the restriction doesn't apply to it, as you note.

Answer 2

It's called a coordinating conjunction.

I figured this out from dictionary.com, which provided this example:

Meaning:

• for the following reason
• because
• seeing that

Example:

I couldn't stay, for the area was violent.

Merriam-Webster's example:

the bill should be listed as paid, for I mailed it in on time

Freedictionary.com has some interesting (if not self-contradicting?) usage note:

Today this use of for is rare in speech and informal writing, and it often lends a literary tone or note of formality.

[...]

But like a coordinating conjunction, for has a fixed position in the sentence, and its clause cannot be transposed to precede the superordinate clause containing the main idea. It is ungrammatical in present-day English to say "For they shall inherit the earth: blessed are the meek."

Perhaps because of this ambiguity in function, for is treated variously with regard to punctuation. Sometimes it begins a dependent clause and follows a comma, and sometimes it begins an independent clause (as if it were a conjunctive adverb like moreover) and follows a semicolon or period (when it is capitalized as the first word of a new sentence).

All treatments are acceptable in standard usage. The difference is really one of emphasis: starting a new sentence with for tends to call more attention to the thought that it introduces.

Freedictionary.com also mentioned the slight possibility that for may get used also in the role of a subordinating conjunction, but when searching for and visiting webpages that explore these definitions, one finds that pages listing coordinating conjunctions always list for, and pages listing subordinating conjunctions never list for.