I think the only honest answer to your question one can give is this: Despite all efforts by scholars to determine the outlines and limits of "Plato's Theory of Forms," these continue to elude us, precisely because Plato never articulates them in a way that settles the matter. In some cases, this is because Plato only manages to allude to "the Forms" without filling in enough of the necessary theoretical details. But in other cases, he seems to supply different theoretical details in different works--in other words, what Plato tells us about the Forms does not always seem to be consistent. He does explicitly mention the things you call "abstract ideas" (though I think he would not be entirely comfortable with this description), such as beauty and justice. In Book X of the Republic, he also mentions a Form of Bed (or Couch), and other Forms for particular things in the world are also mentioned in various Platonic works.

I am aware of no places where Plato explicitly mentions a Form for a kind of weapon (though I am quite sure that he does not mention weapons that had not yet been invented, such as guns and atomic bombs!), but if he supposed there was a Form of Bed, I don't see why he would not also have to suppose there was a Form of Sword. Lots of things "contribute to people's suffering" including even just laws, of course. So on this issue, too, I see no impediment to including Forms of weapons in Plato's ontology, though as I said, he never really offers a whole theory that would allow us to settle this question decisively.

Having an office?

But really, this is the wrong question. There's no such thing as an "official philosopher". There are just people now writing on philosophical issues whose work is taken more or less seriously and respected by a some group, larger or smaller, of other people interested in philosophical issues.

True, nearly all of these people are employed professionally as teachers and/or researchers by universities -- so I suppose they might be said to be "official" in an uninteresting sense (there are not many these days who are like Bertrand Russell with a private income!). But of course it isn't that sort of professional status that matters about a philosopher, but whether they are any good.

So what makes it the case that this writer's work is taken more or less seriously and respected, and that writer's work isn't valued so much? I think I can recognize good philosophy, and hence a good philosopher (I have to say that, having edited one of the philosophy journals for a long time). But what criteria do I use? Now that's a good question!

Yes. There is a book, Wittgenstein and Buddhism, written by Chris Gudmunsen. That's all I know about, but there is probably much more.

One observes an idea simply by having it. For an idea to exist, and for someone to be aware of it, are, for Berkeley, the same thing. To be is to be perceived. You might say: no, the things we are aware of are not ideas but bodies. But Berkeley would say: bodies are ideas, and it is through experience that we know about them. Empiricism holds that experience is the only foundation we have for knowledge, or indeed for any kind of cognition at all, whereas rationalism suggests that we have some other source for knowledge, perhaps some kind of super-sensory faculty of pure intellect. But Berkeley straightforwardly declares: 'Pure Intellect I understand not' (Philosophical Commentaries, sect. 810). All that our senses reveal to us of bodies are their superficial appearances, qualities such as size, shape, colour, flavour etc. A rationalist would suggest that our intellect enables us to penetrate beyond these, and to grasp the underlying substance to which all these various qualities adhere. Berkeley, by contrast, maintains that the sensible qualities of bodies are all that we can know of them, and he dismisses the philosophical notion of 'material substance' as a wholly unintelligible abstraction: 'when I consider the two parts or branches which make the signification of the words material substance, I am convinced there is no distinct meaning annexed to them.' (Principles of Human Knowledge, sect. 17). It is precisely because he is an empiricist, not presuming to overstep the epistemological constraints that sensation places on him, that he ends up claiming that bodies only exist in the mind. Sensation cannot support any notion of mind-independence, simply because we can never perceive an unperceived object.

But you rightly identify a problem in Berkeley's system when it comes to knowledge of the mind itself. Berkeley expressly denies that we can have an idea of the mind (Principles, sect. 27). So then how can we have any knowledge of it at all? And, if Berkeley doesn't have a coherent account of how the mind can have knowledge of itself, then what right does he have to postulate the existence of any such thing at all? It's not that empiricism as such precludes knowledge of the mind. Locke, for instance, split experience into two separate branches, sensation and reflection, the latter of which was supposed to be our source for knowledge of our own minds and their operations. But Berkeley's theory of ideas generates special problems for the establishment of a theory of reflection. These problems were left unsolved in the first edition of the Principles and Three Dialogues. They might have been addressed in the projected second part of the Principles, which was going to be directly concerned with the mind, but this never got finished: 'As to the Second Part of my treatise concerning the Principles of Human Knowledge, the fact is that I had made a considerable progress in it; but the manuscript was lost about fourteen years ago, during my travels in Italy, and I never had leisure since to do so disagreeable a thing as writing twice on the same subject.' (Letter to Samuel Johnson, 25 Nov. 1729). In the 1734 revised second edition of the first part of the Principles, bound up with a revised third edition of the Three Dialogues, Berkeley did insert a few new passages which touched directly on this issue of knowledge of the mind. He suggested that, even though a mind wasn't the sort of thing that we could have an 'idea' of, we could nevertheless have a 'notion' of it. But these new remarks are so brief that it's hard to extract a clear and coherent theory from them. All in all, although the observation of ideas is entirely unproblematic for Berkeley -- it's the notion of an unobserved idea that he finds unintelligible -- the observation of the mind certainly is not.

I don't think this responsibility is confined to those who have thought deeply about an issue. If climate change is a menace to the poor today and to future generations, and if we are much involved in fuelling this menace, then we all have a responsibility to act to slow down and stop this phenomenon. If the responsibility were confined to those who have thought deeply about this, the others could easily get off the hook simply by avoiding deep thought.

Still, I agree that as one who understands the problem better one has a special role to play, namely the role of alerting others to their responsibilities. This is something philosophers can do and should do much more of: Help citizens think clearly and critically about their responsibilities as citizens of their state and of the world. In most cases, this indirect way of doing something about the problem is likely to be more effective than direct action. And it has the additional advantage of helping one's fellow citizens avoid involvement in grave wrongs.

I'm not convinced that we should equate Plato's political philosophy with fascism, although certainly this claim has been made seriously and with rational argument. But let's put that to one side.

It seems to me that there are two questions here. First, should we judge historical figures by the same moral standards that we hold today? And, second, in what sense can someone whose views we find repugnant ever be considered a 'great' philosopher?

The first question paints one directly into a corner: it seems that either we should reject historical philosophers because of the views they held (in which case there would be not much of the history of philosophy left!) or, we are forced to take seriously, over and over again, morally and politically dubious positions. But what does it mean to 'take seriously'? One approach would be a broadly historicist one: Plato's political theory can be understood as rational only given the historical circumstances in which he lived; since those circumstances no longer pertain, the theory is of historical interest only. I have some sympathy for this way of thinking, but I think it is too often used to sweep things under historical carpets and avoid having to take them seriously. But, again, what does that phrase mean? It does not mean just to accept or agree with. Instead it means to analyse and evaluate the position and the arguments put forward for it. If the arguments are found wanting, then so be it; if not, then maybe our own complacent and naive views need to be challenged, or at least the reasons for our views need to be reviewed, strengthened and defended. At any event, surely nothing is more 'fascist' (in a loose sense) than stopping at 'Plato was a fascist'. My answer to the first question is also an answer to the second: a great philosopher is not great (as far as I am concerned) because of his or her conclusions (again, there wouldn't be many philosophers left after the application of this filter), but because he or she has the power to make us think, carefully and critically, and perpetually to raise new issues for us to think about.

Many of the questions and responses in the 'Philosophers' and the 'Ethics' sections of this site grapple with similar problems.

Start with a different case. Take the sentence "Whales are a kind of fish".

Once upon a long time ago, that would have been taken to be a truism. And someone who then denied "Whales are a kind of fish" would probably have been suspected of not understanding "whale" (or "fish") -- whales are "by definition" a particular big kind of fish, it would probably have been said, just as bachelors are a particular kind of unmarried man. Philosophers of the time might even have said it was "true by definition", the kind of thing that is true just in virtue of the meanings of the words involved ("analytic" as some later philosophers would put it).

Yet nowadays we do routinely deny "Whales are a kind of fish". So if it really was once true just in virtue of the meanings of the words, and now it isn't true, we'd have to conclude that the meaning of the words has changed.

But is that right? Have we definitely come to change what we mean by the words "whale" or "fish"? Or is it perhaps that we have changed our beliefs about the way the world is (the nature of species, etc.)? Or is it a bit of both?

Quine's fundamental claim is that such questions don't have determinate answers (for a start, notions of meaning just aren't sharp enough). Our "web of belief" has changed, the interlocking network of sentences we accept as true has shifted. But, he thinks, we can't factor the changes neatly into a change-of-meaning component and a change-of-belief-about-the-world component. It's all a lot messier than that.

And if it isn't a determinate matter, in a particular case, whether change of assent involves change of meaning or change of doctrine, it isn't a determinate matter either whether some sentences are initially true-in-virtue-of-the-meanings-of-the-worlds involved (analytic), and then later not. An all-or-nothing notion of analyticity, Quine argues, does no useful work here. Rather we need some more shaded notions that come in degrees, notions like degree-of-entrenchment into our web of belief.

Now, you might respond, even if things are more complicated in the "whale" case, surely at least in the case of "all bachelors are unmarried men", this could only be rejected if we changed the meaning of "bachelor" or "unmarried" (or "man"). But maybe even that is not entirely obvious. Suppose that it became the case that the only marriages in the traditional sense were weddings of convenience e.g. for immigration purposes, and that such marriages had zero impact on lives otherwise. Rather, a different kind of civil partnership, with different duties and entitlements became the social norm. Then the ideas of (i) a man who is not in a long term relationship and could become a socially recognized partner in a way that over time brings enforceable obligations and (ii) a man who is legally able to contract a marriage could peel apart. Suppose the word "bachelor" went with the first idea. Would that, quite determinately, be a change of meaning? I'm genuinely not sure (given all the life-style and partner-availability connotations of "bachelor"): again, the notion of meaning is arguably too unclear. Yet we'd no longer say "all bachelors are unmarried men".

Ok that was a bit fanciful, and I don't want to insist on the example. But it perhaps gives some colour to the Quinean point that these issues aren't clear-cut in the way that the traditional doctrine of analyticity would have it. (So it isn't that "Quine is entertaining the possibility that we may stumble across some married or female bachelors", but rather he is saying that issues about meaning and change of meaning, for example, aren't nice and sharp and determinate.)

But suppose you are inclined, despite all that, to dig in your heels and insist that "all bachelors are unmarried men" is true in virtue of the meanings of the words involved, and hence change of assent to that sentence must involve a change of meaning. Quine himself might disagree, but the more relaxed latter-day Quinean would probably not be too unhappy, and allow you a few trivial cases of analyticity like this. The argument would remain that the all-or-nothing notion of analyticity applies, if at all, only to such trivia, and is in bad shape for dealing with any more substantial cases of supposed necessary truths.

There is a really nice discussion of these things, if you can get hold of it, at the beginning of Paul Churchland's book Scientific Realism and the Plasticity of Mind. And another nice paper is Hilary Putnam's "It ain't necessarily so" (which you can find in one of the volumes of his Collected Papers).

Please have a look at the question and especially the answer here:

http://www.askphilosophers.org/question/1476

It is interesting how economics in particular seems to offer the most obvious examples of how one's ends are always 'mixed'.

I have a little ego, so I'll offer a little answer.

I agree completely: it's not necessary to have studied philosophy to be able to say sane, sensible things about abortion, love, education and so on. Indeed, it would be very bad news if being able to think well about those sorts of things called for specialized training in philosophy. And in fact, no one on this panel is an authority on what people ought to think about, say, capital punishment. The questions philosophers think about are, as it's sometimes put, essentially contested. It's in the nature of the strange business we're in that no one is an authority on the answers in the way that a physicist might be an authority about the answer to some scientific question. No one should accept the conclusions folks on this panel come to just because we're philosophers, and none of us would want anyone to do that.

What philosophers are often good at, however, by skill, training and inclination, is sorting through the logical and conceptual details that certain sorts of issues present. They are often good at spotting important distinctions, relevant possibilities, potential intellectual traps and so on. Non-philosophers can be good at that too, of course, but it's part of the philosopher's stock in trade.

And so I'd suggest that when anyone reads what a panelist here has to say about some topic, what they should react to is the quality of the reasons and arguments. We hope -- all of us -- that we can say things that people who write in will find well-reasoned and helpful. But our status as professional philosophers doesn't guarantee that we'll succeed, and when we don't, readers ought to reject what we say.

And... since I thoroughly agree with Peter's comments, I'll add that you can read some similar reflections by going to question 1950.