I was reading Beyond Good and Evil and came across this sentence: "For there are scoffers who maintain that it has fallen, that all dogma lies on the ground—nay more, that it is at its last gasp.". So, what is the meaning of "for there are"?
For is a preposition ("for me"), but according to the Collins English Dictionary, it can also be used as a subordinating conjunction, introducing "a clause which gives the reason why you made the statement in the main clause" (so, roughly meaning "because, as, since"), in literary texts.
Here is an example from the King James Bible (1611):
Let him that hath understanding count the number of the beast: for it is the number of a man (Rev. 13:18);
Here is an example from L. Frank Baum's 1900 novel The Wonderful Wizard of Oz:
"By means of the Golden Cap I shall command the Winged Monkeys to carry you to the gates of the Emerald City," said Glinda, "for it would be a shame to deprive the people of so wonderful a ruler."
For more context, this is from a passage depicting Truth as a woman, pursued by philosophers, depicted as men.
"Certainly she has never allowed herself to be won; and at present every kind of dogma stands with sad and discouraged mien--IF, indeed, it stands at all! For there are scoffers who maintain that it has fallen, that all dogma lies on the ground--nay more, that it is at its last gasp."
That use of for is equivalent to "because". It means that dogma may not be standing, for (because) some scoffers say that it is on the ground and dying.
This use of "for" is old-fashioned.
American Heritage Dictionary "for"
(conjunction). Because; since.
There is a long, interesting usage note at that link about this use of "for".