Consequentialism -- also called utilitarianism -- is one of the going theories in moral philosophy. It's supposed to give us an account of what is and is not moral. So, not what morality is, nor why anyone should care about it, but how to tell whether a given course of action is morally right or wrong. I've always found it sort of a weird theory, in that I'm not sure it's really a moral theory at all.
There's a number of different forms of consequentialism, and I can't hope to do justice to all of them. But here's the summary. A consequentialist is someone who believes that the moral rightness or wrongness of a course of action is substantially determined by its consequences.
The first point to note is that word "substantially". Very extreme -- usually, early -- forms of consequentialism hold that the moral status of an action is fully determined by its consequences, but this has largely fallen into disfavour. The basic problem is that not everything that seems morally worthwhile is as worthwhile as its consequences would suggest. It seems like a good thing to be courageous or kind; even though these might have good consequences, that doesn't seem like it exhausts the extent to which these are good.
The second point is the word "consequences". It's pretty much a placeholder term, which gives you the form of a full consequentialist theory, without having much substance. Something that results from the action is what matters to determining its moral status, but exactly what varies depending on the theory.
The earliest consequentialist theories were hedonist (or hedonistic) theories; that is, theories which held that the consequences which mattered were the production of pleasure and pain, where pain is defined to be the strict logical opposite of pleasure. That is, when you're not experiencing pleasure, you are experiencing pain, and vice versa. The more pleasure produced -- or, in other versions, the better quality of the pleasure produced -- the more morally correct the course of action.
Of course, other sorts of consequences are possible. I recall reading one version -- the author escapes me, unfortunately -- where the consequence in question was the Kingdom of God. That is, actions were morally right insofar as they contributed to bringing about the Kingdom of God. (Don't ask me for the technical definition of that concept.)
The third point is the idea of a "course of action". On some versions, called "act-consequentialist", what matters is each individual act that someone performs. So, for every act, its rightness or wrongness is determined by its particular consequences. On other versions, called "rule-consequentialist", what matters is the general course of action that someone is following. So, for every act, its rightness or wrongness is determined by the consequences of actions like that, as expressed by a general rule.
The fourth and final point is the idea of predicting the consequences of a course of action. Exactly how far into the future is one supposed to be able to predict? Very strict versions of consequentialism hold one responsible for all consequences of one's course of action; so, if an act turns out to produce good consequences for one hundred years, but bad consequences for a thousand years thereafter, it would have been the wrong thing to do. Looser versions might hold one responsible for the consequences that can be reasonably foreseen; and very loose versions limit one's responsibility to the immediate consequences.
In any event, that's how one goes about filling in the details of a particular consequentialist theory: how much of the moral status of an action is determined by its consequences (all or most); exactly which consequences matters (pleasure/pain, something else); what a "course of action" is (act- or rule-consequentialism); and how far one has to be able to predict (all, reasonably-foreseeable, or immediate consequences).
So, here's my problem with this theory: why think that this is a theory of what's morally right or wrong? It looks to me like a theory of what's sensible or practical (in the common sense of "practical") to do. It makes sense to do what produces good consequences, and refrain from doing what produces bad consequences. That seems like a pretty reasonable thing to believe. But why believe that an action is right because it produces more good than bad?
There's a host of examples in philosophy for putting pressure on just this point; let me work through just one. Suppose that you have the chance to save someone from a burning building, but only have time and resources to save one. Unfortuately, there are two in the building. One is a world-renowned medical researcher on the verge of curing a serious and generally fatal disease (pick your favourite). The other is your spouse (or someone else very important to you personally).
I agree that it's the sensible thing to do to pick the researcher, and that this can be justified on consequentialist grounds. The reduction of suffering produced by curing a serious disease vastly outweighs any personal suffering caused by allowing one's own mother to die.
I don't agree that it's the right thing to do, though. It's right -- morally right -- if anything is to pay special attention to, and especially care for, those one has a close relationship to. And any moral theory which says otherwise is, to at least that extent, deficient.
Smart consequentialists will leap in at this moment and point out that there are consequentialist reasons to prefer people who will generally choose to save those close to them over important strangers. The basic point is that there are better consequences for having people who adopt this rule (or, who generally but not universally choose those sorts of acts) than not. To my eye, this seems to be admitting that there are consequentialist reasons to not always be a consequentialist, which pretty well torpedoes the theory.
So, am I missing something about why consequentialism is plausible as a theory of morality? Or is it a theory that's been misapplied -- that thinks it's about morality when it's really about practicality?