Almost all theories attempt to divide either people or actions into categories of right and wrong, good and bad. But of course there must be a basis for these judgments, and this basis usually falls into one of four categories (detailed below). Of course, a theory might attempt to combine two or more of these kinds of theories, but such compositions often have more problems than a theory that is unified in what it counts as important for determining right and wrong, since it is easy for theories from different categories to make contradictory claims about the same situation. Without further ado then here are the categories:
An ethical theory in this category judges a person or act based on the reasons the person acting thinks they have for action (as we all know a person’s real reasons may be hidden even from them, judging based on those kinds of reasons falls into the next category). For example, some ethical theories argue that an act is good when the person acting can provide to others acceptable reasons for performing that action. Obviously to give reasons one must be aware of them, and so we categorize such theories as judging based on conscious reasons. Likewise, an ethical theory that argues that an action is right if it is done with the right conscious intentions would fall into this category (some virtue theories). Theories in this category may be criticized because it easy to deceive oneself consciously, for example we may think we have good reasons when we really don’t (the reasons we consciously think of as good are actually faulty), and thus such theories may be seen as letting some people off the ethical hook, so to speak.
Theories that judge based on real motivations are much like those that judge based on conscious reasons, except that they take into account motivations and reasons for action that may be unconscious even to the person acting (although there is nothing that prevents the real reasons/motivations for action from being conscious). I won’t say much more about ethical theories based on real motivations, since most theories based on conscious reasons can be adapted to become theories based on real motivations, and vice versa. Ethical theories of this kind may be criticized because as people often are ignorant of their real motivations it may be difficult for them to tell how they are doing ethically, and how they could improve.
Consequentialist theories judge an action based on its results. Certain states of affairs are better than others under consequentialist theories, and an action that improves the world (perhaps maximally), such that the world is judged to be better after the action than before, is good, and one that worsens the world is bad. Utilitarianism is a classical consequentialist theory, as it claims that worlds with a greater total of happiness are better than those with smaller total. Thus actions that increase total happiness are considered good under utilitarianism, while those that lead to reduced happiness are bad. Typically consequentialist theories are criticized because they would encourage sacrificing one person, against their will, to save two. Although this is a problem for many consequentialist theories it is not the case for all of them, for example if the theory judges outcomes by how well the rights of individuals are preserved then the world in which one person is sacrificed against their will is worse. Consequentialism may be also be criticized because it would blame people when they have made the world worse on accident. Some may feel that people can be rightly criticized for accidents, but others feel that accidents are exempt from moral consequences.
Finally we have intended consequentialism, which is exactly like consequentialism except that actions are judged by their intended consequence instead of their actual consequence. (And perhaps we could further subdivide this category into conscious intended consequence theories and real intended consequence theories.) Much like conscious reasons based theories and real motivations theories, consequentialist theories can be easily converted into intended consequentialist theories and vice versa. Although they no longer blame people for accidents, intended consequentialist theories might be criticized because they seem to reward ignorance.
Of course there is more to an ethical theory than deciding what to base judgments about right and wrong on, but I am not even going to attempt to categorize how theories that fall under one of these broad groups manage this task (there are simply too many possible theories). Perhaps another day.