I think it's a material conditional.

The presupposition is empirical otherwise.

Only people may suppose or presuppose. An act or process of becoming ("to become...presupposes") may imply or entail something. But an action or a process is not a person and so in a literal sense it cannot suppose, presuppose, assume, infer, assert or deny anything.

And yet it's quite clear what Schopenhauer means, assuming 'presuppose' is a correct translation. It's a harmless solecism or a hidden metaphor.

As in "If another 'becomes the ultimate object of one's own will in the same way as oneself otherwise, then one [must] "suffer directly with the other, and feel the other's suffering just as one ordinarily feels only one's own and. likewise, one directly desires another's well-being in the same way as one otherwise desire only one's own".

Like this? Thanks

Thanks. I agree, seems more like an entailment relationship...and, as such, Schopenhauer's use of "presupposes" entails a solecism!

Although on reflection I'm not sure I agree with myself entirely.. A statement a belief can presuppose another statement or belief, I think.... It's so tricky that perhaps it's a case for not pushing too hard to find a rule where any rule will have exceptions!

yep, see what you mean, something like, e.g.. my belief that the dodgers will win the final presupposes that I believe the dodgers exist. To be frank, I'm not entirely sure whether this is bona-fide presupposition. A "presupposition trigger", i thought, can't be a belief....I could be wrong!

They're closely related, of course. One old test to show that A presupposes B is if both A and ~A entail B. (Present king of France and all that.) That doesn't seem to be the case here, so the modern technical sense of presupposition doesn't fit.

Both sometimes seem to run backward "causally", in the sense that if A entails B, that could mean B is a condition for having A, and that's not too far from how "presuppose" is ordinarily used (leaving aside the modern technical sense in philosophy and linguistics).

Now I can't tell if Schopenhauer is saying B is a condition for A, perhaps something you must have first, in temporal order, maybe something you could have by itself without moving on to A; or just that B is part of the meaning of A, a necessary part, that there is no kind of A that isn't B.

There are lots of different sorts of things that can be expressed by saying "A entails B", "A implies B", "A only if B", "No A without B". Some of those things ordinary folks think of as presupposition, some philosophers and linguists think of as implication, presupposition, or implicature (although that one I'm not seeing here).

Maybe it's crystal clear in the German.

(Sorry if this is just stuff you already know.)

No need to apologize, it's a great answer. Got me thinking. I'm going to try and get the original German to get clearer on this. But as it stands, like you stated, it just does not seem to be a technical sense of "presupposition". Technically, I think it's an error, so I am trying to reconstruct it in a more rigorous way. I'm off to find the German, and thanks again!

I think he means that to have compassion for another entails that one suffers directly with the other. So presuppose is meant as a synonym for entail here, as you first stated. If you are trying to say that presuppose cannot be a word to attribute to a verb, then it is perhaps Schopenhauer's idiosyncrasy in his writing but I don't think it takes away from the meaning he was trying to convey.

Yes, thanks, I do agree; and the meaning is very clear. I am just trying to reconstruct his argument in more rigorous terms. He actually is quite sloppy with his terminology at times... have you, for example, noticed his use of the terms "motive" and "incentive."? (in On the Basis of Morality) They are actually distinct concepts for him but he nevertheless uses them interchangeable which obscures his arguments.

They are actually distinct concepts for him but he nevertheless uses them interchangeable which obscures his arguments. — jancanc

Can you give an example of this? When I read that work, he seems to indeed be using the terms "motive" and "incentive" interchangeably. However, I would say he tends to use incentive as a way of talking about the three moral categories he construed (i.e. self-interest, malice, and compassion). So it is almost like a capital "I". Motives seem to be the individual instances that drive a person to do something, which may fit into the incentive of self-interest, malice, and compassion.

Sure. Motives are representations; objects of external perception or thoughts. We see an external object or have a thought and this object or thought either promises us well-being or woe (misfortune). (e.g. I see an ice cream or think of an ice cream and it this perception or thought causes me to get an ice cream). As representations, motives are within the principle of sufficient reason. Incentives, on the other hand, are expressions or states of the will. Specifically, they are desires. As states of the will, they are a part of one's intelligible character and are outside the principle of sufficient reason.

Motives stimulate incentives (in one's character), and the interaction between the two causes actions.

So when Schopenhauer says that the "absence of all egoistic motivation" is the criterion of an action of moral worth, it's not really the full picture. Because the motive interacts with an incentive to cause actions, as I said.
It should be like the "absence of all egoistic motives stimulating the incentive of egoism".

It's pretty weird right?!

Motives seem to be the individual instances that drive a person to do something, which may fit into the incentive of self-interest, malice, and compassion. — schopenhauer1

Yes, but then he has to refine his criterion of actions of moral worth, don't you think? It's not just a matter of the "absence of all egoistic motives"?

So when Schopenhauer says that the "absence of all egoistic motivation" is the criterion of an action of moral worth, it's not really the full picture. Because the motive interacts with an incentive to cause actions, as I said.
It should be like the "absence of all egoistic motives stimulating the incentive of egoism". — jancanc

Yes, I think you are right. Schop had the notion that everyone had a Platonic version of their character that was outside the PSR and thus beyond time/space/causality. People's characters were pretty fixed and their actions could not help but derive their incentives from this fixed character. A character that was truly saint-worthy would be one who was highly incentivized by compassion and whose motives were ones to see the lessening of suffering in others. Most characters were in a large degree incentivized by egoism/self-interest.

It's pretty weird right?! — jancanc

It's weird in the sense that in my opinion, he overmined the idea of Platonic forms. He had it for each species, for each grade of object, for each individual human's character. I just don't buy it as a metaphysical claim, though I find it interesting. His ideas on the willing/striving nature of humans though are extremely compelling and is where I find him most interesting to read. However, I think his ethics can still be useful for understanding ethical claims. I do think there is something to be said for compassion being the basis of ethics. Even his idea that some people's characters are inclined towards compassionate incentives seems to have some merit. However, is it really that fixed? Probably not. Are people's characters somehow beyond space/time/causality? Probably not.

It's weird in the sense that in my opinion, he overmined the idea of Platonic forms. He had it for each species, for each grade of object, for each individual human's character. I just don't buy it as a metaphysical claim, though I find it interesting. — schopenhauer1

The Platonic Ideas, for me, are the weakest, perhaps even most confused, aspect of his philosophy. e.g., it is not clear if they "belong to" world as will or as appearance.