Utilitarianism is a simple ethical theory that a lot of people fail to understand. The reason for the confusions appears to result from approaching the philosophy either too broadly, or too narrowly. Thus, I think its useful to take a look at the core points of utilitarianism, in order to get a clear analysis.
In simplest terms, utilitarianism is the ethical theory that actions are to be judged right and wrong solely by virtue of their consequences, and right actions are those that produce the greatest balance of happiness over unhappiness. With everyone’s collective happiness being counted as equally important.
The main line of objections one hears deals with the claim the utilitarianism conflicts with moral common sense. An argument that best illustrates this line of reasoning is known as the McCloskey Case. This case uses a hypothetical example to illustrate its point: Suppose that a utilitarian finds himself in an area that has a great deal of racial strife. Furthermore, suppose that during his stay there, a black man rapes a white woman, causing a violent backlash to ensue against the black community in search of the culprit. Now, if the utilitarian has the option of testifying against a particular black man (any black man), who happens to be innocent, in order to end the racist backlash and prevent further violence against other innocent people, by the reasoning of utilitarian standards he would be required to allow the conviction of the innocent man to produce a greater balance of happiness over unhappiness. Here, the McCloskey case attempts to show how doing something that would otherwise be considered morally wrong, is acceptable by the principle of utility, as long as the good consequences that result outweigh the bad (such as bearing false witness against one innocent man to prevent the death of dozens of innocent men). However, common sense dictates that it is still wrong to let an innocent man die on the grounds that it conflicts with our ideal of justice, which requires us to treat people fairly and in accordance to the merits of the particular situation. Thus, as an ethical theory that places the demand for utility above the demand for justice, utilitarianism cannot be right as it conflicts with our moral common sense.
A related (less dire) objection against utilitarianism is based on what one might call backward-looking reasoning. Here, you’re asked to imagine a scenario where you promised a friend you’d meetup with him later in the day, but as you prepare to leave you remember that you could instead spent the time reviewing your school work for the upcoming test. By utilitarian standards, it is argued, you are justified in staying home and breaking your promise, because the consequences of you getting a better grade outweigh the irritation your friend might feel for being stood up. Once again, the case can be made that this conflicts with our moral common sense, as most people would want to affirm that your obligations to keeping a promise are not something that can be so easily escaped just for a small gain in utility. The argument maintains that because utilitarianism places such exclusive concern on the consequences our actions will have, it limits out attention only on future results. But, normally, most people think that past considerations are also important, like keeping a promise to a friend. Thus, utilitarianism seems to be faulty, because it excludes backward-looking considerations.
These objections have prompted utilitarians to respond with several rebuttals in defense of their ethical theory. The first line of defense denies that utilitarians conflicts with moral common sense at all, as the examples given don’t sufficiently discredit utilitarianism because one could easily argue that acts such as bearing false witness (per the first example above) and breaking promises to friends (per the second example) don’t result in good consequences. Thus, these acts would not be done or endorsed by utilitarians. Lying under oath can get you in trouble with the authorities, and delay the capture of the guilty culprit. Not to mention, broken promises lead to broken friendships. Merely because one thinks that a particular action will have the best result, it is not possible to be completely certain, and since experience shows the contrary, utilitarians would not condone such behavior. The best response against these utilitarian defenses is that it’s fundamentally weak, as it assumes that utilitarianism and moral common sense must be compatible because morally right decisions always yield good consequences. But it is reasonable to assume that in at least some cases it is possible to achieve a good result by something moral common sense condemns. Therefore, attempts to reconcile utilitarianism with moral common sense fails on principle.
A much better rebuttal made against the claim that utilitarianism conflicts with moral common sense is for utilitarians to just bite the bullet, and say, “Yeah, it does. So what?” After all, there is nothing inherent in the notion that a matter which follows in line with our common sense is necessarily correct. Common sense would also tell us that the sun moves across the sky, as was once believed, but we now know to be false. The impression that the earth is flat and stationary can also be defended rather easily just by appealing to common sense, but that still doesn’t change the fact that the planet is spherical and rotating on an axis as we speak.
As to the qualifier concerning moral common sense, a similar approach can be made. For centuries, white people in American held it as a point of moral common sense that they were superior to other races. Does appealing to common sense make them right? What about a sexist male, whose moral common sense tells him that his misogyny is justified by the superiority of men over women? These are not hypothetical examples; people like this actually do exist, and they do appeal to their moral common sense to vindicate prejudices the rest of us repudiate as absurdly wrong. So, a utilitarian could easily argue that in certain circumstances it is quite appropriate (even necessary) to question whether it is our moral common sense that needs to be discarded in favor of utility.