There is no universally accepted definition of economics. Traditional definitions associate it with a more-or-less undefined concept of wealth. According to one famous but offbeat 20th-century definition, economics as an intellectual discipline studies those aspects of human behavior that (a) deal with “scarce means which have alternative [possible] uses” and (b) are guided by objectives. I would define economics simply as the material aspects of human life and the study of those aspects. Wikipedia defines it as “the social science that analyzes the production, distribution, and consumption of goods and services.” This definition accommodates implicitly the notable fact that most of the goods and services produced or performed by most of the women in the world are not paid for (and thus are not part of market economics, which is what is taught in business schools and at Harvard College), but by restricting economics to social phenomena it neglects material exchanges between humans and the rest of Nature, and thus denies implicitly the existence of ecological economics. The diagram below explains that the study of market economics is part of economics as a social science, and that economics includes ecological economics.
The deepest current issue in economics is how to balance the three kinds of concern that are described in the following diagram:
Let me try now to characterize succinctly the relevant basic views of three categories of people: (1) capitalists, (2) theists and (3) good humanists. Let me for this purpose define capitalists as people who wish and expect capital to grow always more and more, and therefore wish and expect material production and the market to increase infinitely, but who, as capitalists, don’t care whether people other than themselves are thereby rendered materially better or worse off. (All capitalists are humans, and some of those humans may care about the welfare of other people, but that is a feature of their human-ism rather than of their capital-ism.) I think humanists should care about per capita material welfare and should therefore advocate zero population-growth. I also think humanists should care about people in poverty, that is, people who don’t have a decent amount of material welfare. This raises some tricky questions – such as “How much is enough per capita?” and maybe even “How much is too much?” – which we can discuss. (I think humanists should also be concerned about spiritual welfare in this our life on Earth, but that’s another matter, not economics.)
As for distribution, I would suppose that some but not all capitalists would wish it to be not so unfair as to give rise to very destructive forms of violence. (It seems to me, by the way, that such violence is seldom wrought by the destitute; they’re too weak for that; it is wrought by people strong enough to have effective rage.) All good humanists and probably most theists share that wish. (I have in mind theists who, for instance, don’t subscribe to the concept of Armageddon.) Perhaps most humanists and some theists would also wish economic inequality to be moderate enough that the more affluent folks can feel morally at ease with it. And, some humanists and theists may advocate material equality (which I regard as an unfeasible ideal; we can discuss this).
Humanism calls for ecological sustainability (the belief that it would be OK to render the Earth uninhabitable by humans since Nature would carry on without us is hardly humanist), and yet the tension between capitalism and ecological sustainability is going to get worse and worse. It is palpable already. Some theists may feel that God would providentially prevent anything dire from happening to the Earth as the home of humankind, or else that if He wills such dire things, then so be it; but humanists should take seriously the possibility – the likelihood – of catastrophic ecological degradation, and try to prevent and mitigate it. This problem raises scientific and moral questions (combined as in medical science) as to how much of this or that change would be too much for us biophysically. I think it will become an even bigger problem than the somewhat related one of running short of consumable energy.