Why are certain endeavors typically considered to be more meaningful than others? Volunteers like to say that their work adds meaning and a certain form of fulfillment to their lives. Why is volunteerism, in particular, seen to be "meaningful"? Why don't we hear the same claim as frequently from say, lawyers or tax accountants?

I wanted to add a few thoughts prompted by Amy's very interesting response. First, if you're generally interested in the topic of the meaning of life, you might check out Albert Camus's retelling of the story of Sisyphus, which concludes: "One must imagine Sisyphus happy." This might lead one to think that Camus has fallen into the kind of objection advanced by Taylor, but it's not clear to me that he has. In any event, Camus's essay is tricky and complicated, but it is also well-written, rich, and rewarding, I think it well worth the time and effort. Second, if you are interested in the way that a living philosopher grapples with this sort of question, I heartily recommend Susan Wolf's book, Meaning in Life and Why It Matters , which engages in an extended way unparalleled by the work of other recent philosophers that I know with this general topic. Wolf, if I remember correctly--and I may well be misremembering--suggests a similar response to the question of what gives life meaning to that...

Does the belief that everything is matter lead to the belief that the most important things in life are material goods? In other words does the philosophy of materialism lead to the other kind of materialism where money and goods are the most valued things?

I don't think that there is any reason that a materialist metaphysics should lead one to become materialistic. Historically, at least, one of the points of a materialist metaphysics was to bring agents to see that their highest good did not depend on God or an afterlife but could only be achieved in this world, by their own efforts: while there are differences about the nature of this highest good--materialists such as Epicurus, Hobbes, and d'Holbach,, for example, have different conceptions of ethics and also of the highest good--none of them thought that the accumulation of material possessions was the highest good, and although, historically, materialists have tended to espouse some version of hedonism (the best-known materialist ethics, advanced by Epicurus, is a version of hedonism), there is no reason to think that a materialist metaphysics is not compatible with a wide range of (non-theological) conceptions of the highest good, and, indeed, there is no reason to think that a materialist...

Duty, engagement, rules, living a life "conditioned" vs. one free, maybe unconventional, following our own inspiration even if it doesn't seem supported by what we call "common sense". Many of us live a life that often is the result of choices influenced by many different conditionings, sometimes unhappily. It is not easy for everybody to understand what one really wants for himself in this life, and strong moral conditioning prevents radical choices. Where I should find more about this topic ? Thank you.

There are a number of classic works that treat the sorts of issues that you raise. (Interestingly, for what it's worth, relatively few contemporary 'analytic' philosophers have engaged these issues.) Chief among them, perhaps--at least in the Western tradition--are Plato's Republic and the New Testament, both of which, I think, are concerned with the kinds of issues that you mention. More relatively recent works that engage the topics that you mention include Henry David Thoreau's Walden , Martin Heidegger's Being and Time , and Jean-Paul Sartre's Being and Nothingness . (Sartre, of course, is the popularizer of the notion of 'radical choice'.) A very recent book by a living philosopher that treats the issues to which you refer is Susan Wolf's Meaning in Life and What Matters .

Does nature have any meaning? I guess the scientists who like to study the stars and the physical chemists who like to study things at the quantum level find something meaningful in nature. But those people usually say that their isn't any kind of ultimate purpose found in nature.

In "Brains in a Vat," the first essay of his book, Reason, Truth, and History , the philosopher Hilary Putnam considers a thought experiment, according to which an ant crawling along the sand produces what would appear to be an image of Winston Churchill. He asks whether this image would count as a depiction of Churchill, and claims that it would not: it would not count as a depiction or representation of Churchill, because the ant has never seen Churchill, and therefore could not have the intention to depict Churchill. The image, therefore, is not intrinsically meaningful: it would take an observer to notice that the ant's tracings resemble Churchill, and to conclude that s/he has seen a representation of Churchill traced in the sand, thereby endowing the ant's tracings with meaning. Nature as a whole, like the ant, does not seem capable of producing meaning: in order to produce meaningful representations (including pictures or words), there must be an agent who knows how to manipulate those signs....