Title kinda says it all.
The elf Feanor asks some other elves for some boats, they refuse, Feanor kills them and takes the boats. (super condensed version)
Mandos, a Valar, pronounced the Doom of Mandos proclaiming bad things to come if Feanor and his people continue on their path. Feanor gives him the finger and they continue on that path and…bad things happen. (also super condensed version)
Was that a prophecy from Mandos or did he curse them for the kinslaying?
My initial thought was that it was a prophecy. But after reading the text of Mandos’ speech, with the “wrath of the Valar” – I’m going to go with curse. Morgoth similarly cursed Hurin’s family.
I think more of a curse than a prophecy, since large parts of it are actually stuff that the Valar themselves consciously enacted, like sealing off Valinor to them and not embodying dead Kinslayers immediately.
Although “punishment” is a better description than “curse”, IMO. If I say “You’ve eaten my donut, intern. You are going to get yelled at by me, and kicked out of the breakroom for the whole week, and you will consequently not get coffee the rest of the week, suffer caffeine jones, and you will have to eat your PopTarts cold”, is that a prophecy, a curse, or just me recounting your punishment and the inevitable easily-foreseeable consequences?
BTW, it’s “Mandos, a Vala” - Valar is the plural, Vala the singular.
Is it a punishment? I mean, the kinslaying happened and then Mandos was like, “Dudes, if you stay on this bogus path some shit is gonna happen and you will not like it.”
Which implies if Feanor took heed and stopped then and there all would be ok.
One of these days I will remember that. 
The Valar will actively do things to the Fëanorians as a response to their actions. If that isn’t textbook punishment, I don’t know what is. It’s not like the Ban of the Valar was natural law, just magically happening. It was something the Valar had to enforce themselves.
It’s more than implied (contrast Fëanor with Finarfin), but the existence of forgiveness and redemption doesn’t mean the punishment is not a punishment.
To be technically correct (the best kind of correct), his name is Námo. Mandos is just where he lives. Just as his brother Irmo lives in Lorien. Why JRRT did that is anybody’s guess.
And I think it’s a prophecy. Námo told the rebellious Noldor the facts, and it sounded like a curse to them. Námo was the Harry Truman of the Vala. “Give 'em Udûn, Námo!”
I think that, in Tolkien’s worldview, there wasn’t such a great difference between a “prophecy” and a “curse”. It’s simply a true statement about the future.
I am inclined to agree. One of the gifts of Men is that they had a lot more Free Will than Elves did. If you make a prophecy about Aragorn, there is wiggle room. “Either he will rise to the heights of his ancestors, or he will fall into utter obscurity.” If you make a prophecy about an Elf, he’s probably stuck with it.
Doesn’t a curse imply someone put a whammy on you to make life difficult and a prophecy is just letting people know what’s coming if they do “X”?
It could be both, meaning that not only will something bad happen to you if do X, you will certainly do X. (Or will you? Part of the curse could be the resulting mindfuck. And, sure enough, the person ends up doing X.)
There is also the trope that, if you try to avoid your destiny, everything you do just makes it that much more certain to happen.
Take MacBeth, for instance. The witches told him to beware of MacDuff. So MacBeth tried to kill MacDuff. But he only killed MacDuff’s family. So now MacDuff, who had been loyal, suddenly became his arch-enemy.
Given that most of Elvish history was pre-ordained by the Music of the Ainur, I am inclined to believe that Feanor was doomed, regardless of whether Mandos expended any effort or not.
On the other hand, perhaps Mandos was predestined to put a whammy on Feanor.
These chicken-or-egg questions make me dislike determinism.
I think a curse is pro-active, as in “I’m going to exert some supernatural force, either directly or via appeal to a deity, to harm you.”
A prophecy is a prediction of what will happen, and not necessarily with a qualifier like “if you do X, if you don’t do X”. It could be something like: “Your kid will kill you, and bang his own mother.” And there’s no avoiding it.
I think if it was a prophecy, it would have gone something like “Fëanor , and all your host, you’re all so fucked. You are going to piss off and won’t come back unless it’s in a hearse … not so fast, Finarfin&Co…”. It would indicate an awareness of who would repent and who wouldn’t, which isn’t really how the Ban reads to me.
The way it was phrased made it more of a “These are the things we’re personally going to do, and these are the logical, natural consequences of those actions on you, given your immortal nature and the corrupting influence of Arda Hastaina. But it doesn’t have to go down like that.” Real prophesies tend not to have that kind of get-out clause, IMO.
I don’t think it’s a prophesy to say “You’re going to get kicked in the balls” if I then kick you in the balls. Nor is it prophesy to say “in a short while, you’re going to be curled in a tight ball on the floor for a few minutes, crying and calling for you mother” if I know I plan to kick you in the balls.
But kicking you in the ballsThe Ban doesn’t seem like a curse to me, either. A curse is where I manipulate Fate to afflict you with negative consequences that aren’t of my direct action. I, the Delphic Oracle (or we, the Fates), don’t actually tell you to go via Thebes, and I don’t remove the right-of-way signs at the Davlia road crossing.
Whereas the Valar actively enforce the Ban. MandosNámo actively held the fëar of the Fëanorians from re-embodiment , for instance (I’m uncertain exactly how long - for just a very long time, until the War of Wrath, or longer). You don’t get called Imprisoner* just for playing along with some natural moral law.
* I’m aware the etymology changed, but the original meaning does explain Tolkien’s thinking in this regard. Mandos is an active jailkeeper.
Now I’m wondering if “hastaina” and “hanstovánen” share etymologic roots. Gotta go rummage around in BOLT for a while now. Thanks!!
I don’t thinks so - the meaning of hanstovánen is uncertain, as far as I can tell, but the earlier version was Vanë Hansto
I don’t think Hansto has ever been translated. Vanë could be vanë, “beautiful”, or maybe vánë “went away”. Or something else entirely. I think the “went away” sense is more in keeping with the function of Mornië, and I don’t think “beautiful” would be appropriate for the Ship of the Dead’s moorage
The original, rejected name was Mornielta, which AIUI is Mornië (the ship, Black Grief) + elta (thrust.
whereas the root of hastaina is hasta, “to marr”. Don’t seem related.
That kind of get-out clause is the exact purpose of “real prophecies”: Repent, or else.