Plato has a number of things to say about moderation in the Republic, but I think the most important one is where he associates moderation with the proper functioning of the appetitive part of the soul. The good news about that part is that it is responsible for the basic functions that keep us alive, such as eating and drinking, and also make us inclined to reproduce. The bad news is that the appetites have a tendency to excess, which--if not prevented by the ruling part of the soul (the reasoning part)--will lead us to do things that are not all things considered really good for us. Hence, moderation in a person will be the result of the "agreement" on the part of the appetitive part to the rule of the reasoning part. The same goes in a city: left to themselves, the craftsmen will have a tendency to excess and dissolution, but when ruled by Plato's philosopher-rulers, the proper functioning of this "appetitive" class of people will allow the whole state to become moderate. Unless and until they agree to allow the best rulers actually to rule, there will always be a high degree of risk that the state will slide into immoderation.
I hope this helps!
I am much more familiar ... with human (or human-like) beings who lust after young peasant women than I am with ones for whom the very experience of lust is unimaginable ...
To say nothing of the doctrine, central to one of the major monotheistic religions, that God became a flesh-and-blood human being while somehow remaining an omnipresent and perfect spirit who continued to rule the universe. It's hard to see how the Zeus story is "significantly less plausible" than that!
I'm sympathetic to most of what Professor Heck says, if we consider things from a deontological or even a consequentialist point of view, where the relevant consequences are external to the agent. Fantasy does not violate anyone's rights, and fantasy that never motivates action will not result in actions that harm anyone. But I think there is a plausible way of looking at things that would still find fault with fantasizing about having sex with children, and that would come from the aretaic (or virtue-theoretic) way of thinking, according to which the primary bearer of value is to be found in characteristics of agents. One who indulges in fantasies about sex with children is doing something that both reflects--and also perhaps perpetuates and sustains--a certain trait of character that we might think is not entirely wholesome or admirable. To the extent that we can regard one who indulges in such fantasies as having a trait of character that is improvable, we might also think that some attempt to eliminate or at least diminish the inclination to indulge in such fantasies would result in that person having some improvement in character. It may be that habituation can only go so far, and that virtue theorists (such as Aristotle) overrate the extent to which one can habituate better character traits, but it certainly does seem that a virtue theorist could find the character of someone who tends to indulge in such fantasies at least improvable, and this way of looking at things does, I think, put a different face on this kind of case than what Professor Heck has indicated.
In my opinion, Plato's views on knowledge shifted around in a number of important ways over his career, but you're right to say that he always treats knowledge as having at least some innate aspects. In Book V of the Republic, for example, he characterizes knowledge as a kind of power that is innately within us, but--as a power, rather than a state--this account also recognizes the possibility of developing that power, or allowing it to wither. Much of the discussion of Books VI and VII of the Republic concern how to develop this power--how to "empower it," as it were) through the right educational curricula and with the use of what Plato calls "summoners" (by which he means things that summon the exercise of this power, rather than the inferior cognitive powers of belief or sense perception. There is, accordingly, a social aspect (via education) even in Plato's account.
When philosophers these days talk about "social epistemology," it can mean various things. But a "social theory of knowledge" would seem to imply that knowledge is, by its very nature, a social phenomenon. The place to look for this sort of account (if I have understood you rightly) in the ancient world would be in the writings of the group known as the Sophists, some of whom seemed to think that knowledge was a (purely) social construction. I am not aware of too many contemporary philosophers who accept such a view, but I hope my answer has helped at least a little!
It sounds to me as if what you need to do is to have a frank conversation with your partner about things. Sexual attraction for a partner can ebb and flow, and one option might be that some good communication would improve things between the two of you on that front. Alternatively, you could stay together in an "open" relationship, where the value of your partnership can be preserved but not at the cost of your sexuality. The point is that between the two of you, communicating well about what you have and what you (now) lack, there might be some creative problem-solving that would give a more optimal result than the options you are currently considering.
I don't see what is so good about brevity in language. What is wrong with lots of synonyms? You then get to choose which word to use. Perhaps it seems that it does not matter, since the choice is between equivalents. Well, they may mean the same thing but they don't sound the same or look the same.
It is worth trying to avoid a Gradgrind theory of semantics!
Let's take your second question first: Is it immoral?
First, what counts as immoral will reflect which general theory of morality one has in mind. If you shift away from the having sex part to the getting drunk part, I can imagine that some virtue theorists would think that this alone qualifies as non-virtuous, and thus the decision to have sex being made under non-virtuous conditions. A consequentialist would take into consideration other factors, such as reasonably expected outcomes of drunken behavior (such as lapses in the prudent use of contraception, for example). Given that decisions to have sex can have morally significant consequences, it does seem that the impairments that we all know go with being drunk are morally significant ones. Deontologists stress personal autonomy, and while the decision to get drunk might be made autonomously, it is more difficult to regard the behavior of very drunk people as exhibiting a morally appropriate level of autonomy--including most importantly, the kind of autonomy that goes with the giving of "informed consent." So, to answer your question very generally, I think it is fair to say that at least many cases of two people having sex when they are drunk will qualify as having significantly morally negative features. These problems incline me to think the situation actually does become immoral if one of the parties is so drunk as not to be capable of rational deliberation, if the other (however impaired) can still manage some degree of rational deliberation. Make the situation more uneven in terms of degree of drunkenness, and yes, it looks bad to me!
Is it rape? In the situation I just described, it does begin to look like it belongs at least in that general territory, because it becomes more of a case of taking advantage of another's inability to give informed consent. But if both are out of their wits to an equal degree, it seems more difficult to think of the situation as one of rape. But even so, I would want to know more about how each one came to be drunk, and whether there was coersion or manipulation that led to this condition. If so, it again moves closer to rape.
But to go in the opposite direction for a moment: If a happily and sexually active adult couple decide to celebrate an anniversary of some sort (say) by getting drunk together and having sex, we might still have some reservations about their decision-making, but I think "rape" and "immoral" would not apply. So, I think the specifics of the situation will make a big difference in how we would want to answer your question for different cases.
Interesting question. Here is a possible example: In Plato's Protagoras, Plato has Socrates and Protagoras argue about whether there is just a single virtue (despite the different names for virtues, such as "justice" and "courage" and "wisdom" and so on), or whether there are several different virtues, corresponding with the different names. So one might think that Plato decided to take up this topic, because he thought it was one that was controversial or under discussion at that time. To the best of my knowledge, however, no one believes in "the unity of the virtues" anymore. But even if there is someone out there who does, I think it might still be true to say that the view is not taken seriously by "most contemporary professional philosophers," as you put it. I'm sure there are other instances of "dead" theories, as well.
I notice that your question hasn't been answered yet, but it has been waiting for one for a while. I feel a little out of my depth here, but just to provoke some further response(s). I'll take a shot.
Your question is really about what it means to say that something causes something else. If we think of causation as "deterministic," then the laws of causality work in such a way as to have it be that a given cause will always produce a given effect, and the appearance of this effect can be wholly explained in terms of that cause. There are some scientific fields that seem to work this way--classical mechanics, for example. But then, even in the field of physics, it seems that at some levels this (deterministic) conception of causation seems not to apply--for example, within quantum mechanics. Those who explain what is called the "indeterminacy" at this level might explain it in different ways, but at least in terms of explaining and predicting, it looks like the simplicity of a deterministic model of causation is problematized here.
But if you look at most sciences outside of physics, the very notion that causal explanations are deterministic does not apply. Consider a widely accepted and thoroughly scientifically examined example: smoking causes cancer. Does this causal claim imply that either absolutely everyone who ever smokes gets cancer, or else the claim is false? Of course it doesn't! The same lack of complete determinism may be observed in most of medicine--but that does not prove that "medical science" is somehow a misnomer.
But now extend that to the cases you are asking about. The explanation of the prevalence of PTSD among soldiers and former soldiers is very obviously to be explained by their exposure to the horrible things that they experienced in war zones. Does this causal explanation require that everyone who is in a war zone will get PTSD? Of course not--no more than the idea that every smoker will get cancer (or everyone who falls out of third-story window will die, or everyone who drives when drunk will get in an accident, or ... you get the point). Those who seek to undermine our concerns about bullying or sex abuse with "arguments" like the ones you have mentioned simply do not understand the very nature of causal explanation in the biological or social sciences--and probably don't even understand causal explanation, period (since, as I say, even in some areas of physics deterministic assumptions seem not to apply).
I hope this helps! (Others...?)