Ethics is one of the major branches of philosophy and an ethical theory is part and parcel of all philosophies broadly conceived. The list of the greatest ethical theorists includes classic authors such as Plato, Aristotle, Aquinas, Hobbes, Kant, Nietzsche as well as the more recent contributions of G.E. Moore, J.P. Sartre, B. Williams, E. Levinas. The aim of ethics has been viewed in different ways: according to some, it is the discernment of right from wrong actions; to others, ethics separates that which is morally good from what is morally bad; alternatively, ethics purports to devise the principles by means of which conducting a life worth to be lived. Meta-ethics if the branch of ethics which is concerned with the definition of right and wrong, or good and bad.
What ethics in not
First, it is important to tell apart ethics from other endeavors within which at times it risks being confused. Here are three of them.
(i) Ethics is not what’s commonly accepted. Each and all of your peers may regard gratuitous violence as fun: this does not make gratuitous violence ethical within your group. In other words, the fact that some action is typically undertaken among a group of people does not mean that such action ought to be undertaken. As philosopher David Hume famously argued, ‘is’ does not imply ‘ought.’
(ii) Ethics is not the law. In some cases, clearly, laws do incarnate ethical principles: mistreatment of domestic animals was an ethical requirement before becoming the subject of specific legal regulations is different countries. Still, not everything that falls under the scope of legal rules is of significant ethical concern; for example, it may be of little ethical concern that tap water be checked by appropriate institutions several times a day, although this has of course great practical importance. On the other hand, not everything that is of ethical concern can or should motivate the introduction of a law: people should be nice to other people, but it may seem bizarre to make this principle into a law.
(iii) Ethics is not religion. Although a religious view is bound to contain some ethical principles, the latter can be (with relative ease) extrapolated from their religious context and independently evaluated.
What is ethics?
Ethics deals with the standards and principles that a single individual lives up to. Alternatively, it studies the standards of groups or societies. Regardless of the distinction, there are three main ways to think about ethical obligations.
Under one of its declinations, ethics deals with the standards of right and wrong when referred to actions, benefits, virtues. In other words, ethics then helps defining what we ought or ought not to do.
Alternatively, ethics aims at discerning which values ought to be praised and which ones ought to be discouraged.
Finally, some view ethics as related to the search of a life worth being lived. Living ethically means to do one’s best to undertake the search.
Is ethics grounded on reason or sentiment? Ethical principles need not (or not always) be grounded solely on rational considerations, ethical constraints seem to apply only to beings that are capable of reflecting on their own actions as authors such as Aristotle and Descartes have pointed out. We cannot require that Fido the dog be ethical, because Fido is not capable of reflecting ethically on his own actions.
Ethics, for whom?
Humans have ethical duties that extend not only to other humans, but also to: animals (e.g. pets), nature (e.g. preservation of biodiversity or ecosystems), traditions and festivities (e.g., fourth of July), institutions (e.g. governments), clubs (e.g. Yankees or Lakers.)
Future and past generations?
Also, humans have ethical duties not only towards other humans that are presently living, but also to future generations. We have a duty to give a future to the people of tomorrow. But we also may bear ethical obligations towards past generations, for example in valuing the efforts that have been made in achieving peace around the world.
What is the source of ethical obligations?
Kant believed that the normative force of ethical obligations proceeds from the capacity of humans to reason. Not all philosophers would agree to this, however. Adam Smith or David Hume, for example, would rebut that what is ethically right or wrong is established on the basis of fundamental human sentiments or feelings.