[Godstud]

If you don't remove a quote you cannot confirm, or at least acknowledge that he might have said it, you are passing on flawed or incorrect knowledge.

Given what Marx has said about anarchism and anarchists, I find this quote to be absolutely without merit, and likely not something he ever said.

[Bulaba Khan Jones]

To return on our issue. I don't think that one should remove a quote that one cannot confirm, especially in such case, for Marx' work is vast, and it is extremely hard to find whether or not Marx said this phrase. Neverthless I think that I finally will remove it, because the text where the quote lies has nothing to do with Marx and communism etc., therefore the whole passage is not "vital". It is a footnote, actually! (That's why I wouldn't want to put a footnote. I don't really like the footnote-on-footnote thing.)

That's good you are going to remove it, but your reasoning doesn't make sense to me. As an editor, you have an ethical duty to fact-check and ensure what you are editing is truthful, to your knowledge.

I can claim "Marx said, 'I cannot lie, for I like big butts.'" I provide no source or attribution whatsoever. If you cannot find any source for the quote I claim is true (and you have the right to use your intellect and reasoning to deduce, logically, that the quote in question is highly suspect, just like a quote supposedly by Marx in support of anarchists which does not track with Marx's well-known, recorded opinions on anarchists), as an editor, you have an ethical standard involved which should compel you to either insist the quote be removed, marked as apocryphal, or reworded in context like I suggested: "A story goes that Marx said..."

Do you find yourself confused often about what to do when you can't find any evidence about a quote/attribution's existence? The solution was exceedingly clear from the beginning: if you can't find any evidence of the existence of a supposed quote/attribution, it doesn't necessarily need deletion, but it needs a footnote or marker clearly pointing out no source could be found.

Are you yourself an anarchist? I'm very unclear how any of this is confusing to you. It's ethics 101, and as @Godstud points out, your job is to avoid passing on things that are untruthful by noting in the text that there's no source for a quote.

[Godstud]

"Marx said, 'I cannot lie, for I like big butts.'"

I've heard it said that this was true.

[ingliz]

the text where the quote lies has nothing to do with Marx.

And much to do with Bakunin, it seems: "We [anarchists] must be the invisible pilots guiding the Revolution."

Our aim is the creation of a powerful but always invisible revolutionary association which will prepare and direct the revolution. We must be the invisible pilots guiding the Revolution.

Bakunin quoted in S. Dolgoff (1980) Bakunin on Anarchism.

nothing to do with Marx.

Bakunin was notorious for constantly creating, on paper and in his imagination, secret conspiracies run by hierarchical authorities, with himself at the top—conspiracies which were to act behind the scenes of the mass movement... Marx had declared that he was against the formation of sects, with their own dogmas, inside the workers’ movement. (Price 2017)

Marx claimed that they would dissolve in the actual course of the popular struggle. The historical process would produce the correct general direction. Therefore he opposed any factions based on specific, pre-established, political views, within the International. But, it would be a perverse reading of Marx to have Marx say, "There cannot be a revolution without anarchists", when Marx believed that he knew the course which history would take. He was sure that the workers would form political parties and run in elections; that this would lead, somehow, to the workers forming their own states and then nationalizing the economy as the beginning of communism.

[Rancid]

This situation sounds very easy to deal with.

Tell the author
Can you find me a quote? If not, then this will be removed.

Sounds straight forward.