Sometimes when I am talking about economic systems with other people, it often feels as if we're talking past each other. With capitalists, often the standard answer is that the free market will take care of a problem, with very little details to back it up. With communists, capitalism is often talked about as a great evil and that the ideal economic system would have no element of capitalism included, also with very little details to back it up. Needless to say, I don't agree with either camp.
Capitalism the descriptive theory
Part of the reason that I could never agree with anyone who advocates the abolishment of capitalism is because of the thought that capitalism will always be around. Capitalism as a descriptive economic theory is about independent agents in a free market adjusting their production, according to the price set by demand and supply, to form a quasi-stable economy.
With resource scarcity and without centralization of production, capitalism would then be what emerges naturally. This would be regardless of what the resources are or what capital actually is. Whatever the resource, if it's scarce then capitalism is the economic system that is used to trade it in a decentralized system. Whether it's food, tangible products, intangible products, programmers, designers, fame, etc., it's going to be capitalism that trades the resources using capital, be it money, food, minerals, political influence, good will, etc.
The only way capitalism could be avoided entirely is either to have strong centralization, isolation between all small communities, or an abundance of resources. With my preference for decentralization, having no particular desire for isolationism, and knowing that resources are still scarce, I usually don't get a good feeling from people who clamor for the abolishment of capitalism. Although there's a good case to abolishing the application of capitalism to certain resources such as food, of which the world produces enough to feed everyone. (Good food, on the other hand ...)
Capitalism the ideology
On the other had, capitalism is also an ideology. It's the belief that capitalism as an economic system is the end-all and be-all of economic systems. Proponents often claim that the free market is the solution to any problem that comes up. When pointed out problems that occurred in actual capitalist societies, the typical response is that their free market is not free enough, that such problems would go away if they had a true free market. And like other economic ideologues, their supporting arguments tend to be rather hand-wavy.
And similar to communists who say there have never been a true realization of communism, there are capitalists who say that there have never been a true realization of capitalism. Fair enough. I might even care if I was an ideologue, too. However, having a science-oriented worldview, I place far higher value on observations of what happens in the real world, and I don't think much of vague ideals.
So is capitalism good or bad?
For me, the answer is both yes and no. There's no question that capitalism as practiced today, especially in countries such as the United States, has some rather severe shortcomings (unavoidable to some, solely the fault of capitalism to others). However, it's much more uncertain whether institutionalized capitalism far outstrips the alternatives in production that it's more than worth the shortcomings. I don't think so, but it's a question that is still very much unsettled, at least for impure forms of capitalism (and anyone who says otherwise probably has an overly simplistic view of the world).
On the other hand, the economies of today are extremely large scale, so I would oppose any attempt at abolishing capitalism. The only way to get rid of capitalism, besides cutting off all small communities from each other, would be to centralize everything. And given the horrible complexities of a large scale economy, not to mention everyone having different demands, a centralized economy would be hopeless. And then there's the bit about centralization meaning a small number of people wielding a great amount of influence, which is something I don't like. And for all I know, Stalinist Russia and Maoist China may have ended up the way they did because they focused so much on abolishing the Great Evil Capitalism and not so much on forming a classless society.
But at the end of the day, I can't really bring myself to care much about whether capitalism is good or not, especially considering that there could be tons of (rather meaningless) debate on exactly what capitalism is supposed to be. I care much more about specific economic plans and how they would influence the economy and myself. In fact, I have the belief that humans as a whole will approach an ideal economic system as it makes small changes here and there, discovering what works and what doesn't, with things getting better as humans as a whole become more rational and compassionate.
Whether the ideal is capitalism, communism, or something else entirely is not something I care much about. But I trust we will head towards such an ideal as the human spirit improves, and I have high hopes that it will steadily improve with better education and technology. Although I often have my moments of doubt ...