Definition: Ethics is the systematic philosophical study of morality.
But what's the difference between 'ethics' and 'morality'? Don't they mean the same thing? Not really. Given our definition we should be able to infer that 'ethics' names a field of inquiry while 'morality' names the object of an inquiry. 'Morality' is the behavior or codes of behavior of a given group, while 'ethics' is the attempt to understand and justify that behavior. So, an ethicist (i.e., someone who does ethics) is a philosopher who analyzes:
Now we should also note that a person may study ethics without being moral, just as a person may be moral without knowing anything about ethics. This should not be too surprising since we see many similar examples: an ornithologist studies birds without being one! However, what normally motivates the study of ethics is a deep desire to know what is right and wrong and to be able to consistently apply that knowledge in all aspects of our lives. It would be frustrating, to say the least, to be condemned to go through life guessing at which actions are proper and which not. And yet, if one doesn't study ethics, or at least put together some elementary ethical system, this is precisely what one must do. In fact, most people have some ethical system, some intellectual framework which guides their behavior. This is usually a patchwork system made of scraps taken from different sources. But if ethics is given very little thought one is as likely as not to end up with an inconsistent ethical system which will collapse upon itself with only moderate external pressure. To avoid this, we need to apply philosophical scrutiny to our so called 'moral' behavior. Only then can we have some assurance that we are behaving as we ought.
Prescriptive - moral principles are grammatically formulated as imperatives (i.e., commands) to emphasize the obligation which lies behind the proposed action
Universalizable - moral principles are not restricted to particular individuals or groups but must be applicable to any moral agent in relevantly similar circumstances
Overriding - a moral principle should be the primary consideration in action assessment and trump other considerations
Public - a moral principle presupposes social interaction (how can we be under moral obligations if there is no other to be obliged toward?)
Practicable - moral principles must be achievable by the average moral agent (we don't want moral principles prescribing supererogatory actions, we don't want to mistake a moral ideal for a moral principle)
These criteria are not universally accepted by all philosophers, as we shall see. However, they are an adequate guide to our intuitions about what makes something moral.
It is important to recognize the difference between factual propositions and normative claims because they serve radically different functions. Descriptive language helps us understand the environment in which we live which is vital for our continued survival. Normative language, on the other hand, expresses our desires beyond mere survival; it helps us form a concept of what we want our lives to be, or the meaning we wish to find in it.