Tried posting this on reddit and got no responses. Hope someone can take the time to review this.

I've always wanted to have more words to interpret and comprehend this section in the Lysis [218d-221d], and it kind of clicked with me just now. Hoping for some other ancient heads to confirm this or point out what I might be missing.

When Plato investigates the idea of the neither-good-nor-bad having philia towards the good, as the only possible outcome of his preceding investigation, he delves into this question of cause and sake. He says that the neither-good-nor-bad (ngnb) must be friends with the good out of some cause, and for the sake of something further. He first finds that it must be because of the (mere) presence of some bad, and for the sake of another friend. He then finds the chain of further friends to end at the "first friend". And then he worries that since the bad is the cause, the first friend is really for the sake of the bad, the argument being "take away the bad, and the good is no longer a friend." Finally, he saves the good by finding that there are ngnb desires, desires which are not because of anything bad, but because of something ngnb. So take away the bad, and the first friend now still remains.

It seems like "sake" and "cause" of friendship here can be mapped easily to Aristotle's efficient and final causes, respectively, despite Plato's deliberate conflation towards the end. When Plato mentions "cause", he is mentioning some presence of bad, a bad which is distinct from the ngnb thing it is present in, since it has not fully corrupted its ngnb host. This seems clear to be efficient cause, since it is something distinct from the thing itself which causes some thing to take place (that is, friendship). For "sake" of friendship however, Plato in that passage also explicitly mentions the object of sake as being distinct from the friend in question, so that whether it is also a friend is then up for inquiry. Common notion of the word "sake" (Plato uses "διά," but its translation to "sake" seems unanimous) tells us that it is simply whatever the end of a certain purpose is intended to be. This, again, seems to clearly be final cause, which details the cause of purpose.

Plato does then conflate the two when saying the first friend is for the sake of the bad, but it seems he is rather genuinely disproving any potential false dichotomy between the categories of cause. For what he shows is that when something is done (like gaining friendship) for the purpose of achieving good, that purpose can many times be seen as the purpose of eliminating a bad (even though Plato shows this interchangeability isn't always true). And from there, this purpose of friendship to eliminate a bad (which is a final cause) can be seen to necessarily have a further cause (an efficient cause), that being the presence of bad -- the purpose could not exist if it did not have a present bad to refer to. And through that, the final cause seems to only be a product of specific efficient causes, these being the presence of bads or ngnbs. At least, this is by the Platonic arguments put forth, and of course the definitions of sake and cause here do not necessarily apply across the rest of the dialogues in the same way.

So, is this BS or does it make sense? Is there anything between these two pairs of terms that don't map as well on to each other?