Back to the usual program. I'll try to explain and define my terms so that it is as accessible as possible. Of course, I may do a piss poor job of it, or may sound condescending, so apologies in advance.
The word 'consequentialist', is not likely to be familiar to most laymen, but I think the word 'utilitarian' is. Now, when people talk about utilitarian ethics, they are saying that the right action is one that results in the greatest good for the greatest number of poeple. Strictly speaking, utilitarianism is hedonistic. When it talks about good, it talks about pleasure only. i.e. physical pleasure, intelectual pleasure, other types of pleasure etc. So, to clear a few things up, utilitarianism is a subtype of consequentialism. So, when we talk about consequentialism, we talk more broadly. The good is not just pleasure, it can be other things like life, freedom, or anything else that contains intrinsic value. We could even have multiple things which simultaneously have intrinsic value.
What do I mean by intrinsic value? Intrinsic value can be opposed to instrumental value. Instrumental value refers to things we value only because they lead to other valuable things. Intrinsic value refers to things we value in themselves. So, some things have only intrinsic value, some have only instrumental value, and some can have a mixture of both instrmumental and intrinsic value.
So, how would consequentialism work? Lets say that there is a moral dilemma between two courses of action A and B. We look at the consequences of each action. Some of the consequences will have intrinsic value, some instrumental. We translate this instrumental value in terms of the intrinsic value it provides. So, then we see which set of consequences provides more intrinsic value. The action which results in the most value is the right action. In short, consequentialism basically says that the ends justify the means.
There are some variations. Which is more important, actual value, expected value, average value, total value? While that would actually be an interesting discussion, I dont plan to have it here (unless enough people request to have it) There is also a variant called rule consequentialism where the right action is one the follows a rule which will produce the best consequences on average.
There is also indirect consequentialism. Indirect consequentialsim divides the theory into two parts. One is the right-maker, the other is the decision procedure. Indirect consequentialism still says that what makes an action right is that it provides the best consequences. However, since directly calculating the consequences all the time probably makes one make poor decisions since we spend more time calculating and less time doing, it is better to use a reliable decision procedure which is more likely to tell you what the right action is. e.g. some rules of thumb etc.
Hence, it is not the case that consequentialists would necessarily go around violating rights willy nilly. So what exactly do I find wrong with consequentialism? The judgement of actions as right or wrong still depends on what the consequences were. But even though this violates some of our moral intuitions, I won't harp on this particularly. Consequentialists will say that this is not a bug, but a feature and arguing this point often just breaks down into admitting that we have different intuitions about morality. However, there are a number of criticisms of consequentialism that I can offer.
1. Consequentialists need a meta-ethical theory of value. What connects the fact that something is valuable to the fact that it is an appropriate thing to be pursued (in the context of a moral theory)?
2. Heirarchy of values. Given that more than one type of thing are intrinsically valuable, which is the most important, and how do you justify making that standard universal?
3. There are some horrific things that consequentialists may have to accept if they are to be consistent. E.g. Survival lottery etc.
More criticisms may follow in Consequentialism (2). I will also expand on the three that I offered