I. DEFINITION OF ETHICS
Rushworth Kidder states that "standard definitions of ethics have typically included such phrases as 'the science of the ideal human character' or 'the science of moral duty' ".
Ethics, sometimes known as philosophical ethics, ethical theory, moral theory, and moral philosophy, is a branch ofphilosophy that involves systematizing, defending and recommending concepts of right and wrong conduct, often addressing disputes of moral diversity. The term comes from the Greek word ἠθικός ethikos from ἦθος ethos, which means "custom, habit". The superfield within philosophy known as axiology includes both ethics and aesthetics and is unified by each sub-branch's concern with value. Philosophical ethics investigates what is the best way for humans to live, and what kinds of actions are right or wrong in particular circumstances. Ethics may be divided into three major areas of study: * Meta-ethics, about the theoretical meaning and reference of moral propositions and how their truth values (if any) may be determined * Normative ethics, about the practical means of determining a moral course of action * Applied ethics draws upon ethical theory in order to ask what a person is obligated to do in some very specific situation, or within some particular domain of action (such as business)
Related fields are moral psychology, descriptive ethics, and value theory. Ethics seeks to resolve questions dealing with human morality—concepts such as good and evil, right and wrong, virtue and vice, justice and crime.

II. PHILOSOPHIES

A. SOCRATES
Socratic method
Perhaps his most important contribution to Western thought is his dialectic method of inquiry, known as the Socratic method or method of "elenchus", which he largely applied to the examination of key moral concepts such as the Good and Justice. It was first described by Plato in the Socratic Dialogues. To solve a problem, it would be broken down into a series of questions, the answers to which gradually distill the answer a person would seek. The influence of this approach is most strongly felt today in the use of the scientific method, in which hypothesis is the first stage. The development and practice of this method is one of Socrates' most enduring contributions, and is a key factor in earning his mantle as the father of political philosophy, ethics or moral philosophy, and as a figurehead of all the central themes in Western philosophy.
To illustrate the use of the Socratic method; a series of questions are posed to help a person or group to determine their underlyingbeliefs and the extent of their knowledge. The Socratic method is a negative method of hypothesis elimination, in that better hypotheses are found by steadily identifying and eliminating those that lead to contradictions. It was designed to force one to examine one's own beliefs and the validity of such beliefs.
An alternative interpretation of the dialectic is that it is a method for direct perception of the Form of the Good. Philosopher Karl Popper describes the dialectic as "the art of intellectual intuition, of visualising the divine originals, the Forms or Ideas, of unveiling the Great Mystery behind the common man's everyday world of appearances." In a similar vein, French philosopher Pierre Hadotsuggests that the dialogues are a type of spiritual exercise. "Furthermore," writes Hadot, "in Plato's view, every dialectical exercise, precisely because it is an exercise of pure thought, subject to the demands of the Logos, turns the soul away from the sensible world, and allows it to convert itself towards the Good."
Philosophical beliefs
The beliefs of Socrates, as distinct from those of Plato, are difficult to discern. Little in the way of concrete evidence exists to demarcate the two. The lengthy presentation of ideas given in most of the dialogues may be deformed by Plato, and some scholars think Plato so adapted the Socratic style as to make the literary character and the philosopher himself impossible to distinguish. Others argue that he did have his own theories and beliefs, but there is much controversy over what these might have been, owing to the difficulty of separating Socrates from Plato and the difficulty of interpreting even the dramatic writings concerning Socrates. Consequently, distinguishing the philosophical beliefs of Socrates from those of Plato and Xenophon is not easy and it must be remembered that what is attributed to Socrates might more closely reflect the specific concerns of these thinkers.
The matter is complicated because the historical Socrates seems to have been notorious for asking questions but not answering, claiming to lack wisdom concerning the subjects about which he questioned others.
If anything in general can be said about the philosophical beliefs of Socrates, it is that he was morally, intellectually, and politically at odds with many of his fellow Athenians. When he is on trial for heresy and corrupting the minds of the youth of Athens, he uses his method of elenchos to demonstrate to the jurors that their moral values are wrong-headed. He tells them they are concerned with their families, careers, and political responsibilities when they ought to be worried about the "welfare of their souls". Socrates' assertion that the gods had singled him out as a divine emissary seemed to provoke irritation, if not outright ridicule. Socrates also questioned the Sophistic doctrine that arete (virtue) can be taught. He liked to observe that successful fathers (such as the prominent military general Pericles) did not produce sons of their own quality. Socrates argued that moral excellence was more a matter of divine bequest than parental nurture. This belief may have contributed to his lack of anxiety about the future of his own sons.
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There should be no doubt that, despite his claim to know only that he knew nothing, Socrates had strong beliefs about the divine. According to Xenophon, he was ateleologist who held that god arranges everything for the best.[32]
Socrates frequently says his ideas are not his own, but his teachers'. He mentions several influences: Prodicus the rhetor and Anaxagoras the philosopher. Perhaps surprisingly, Socrates claims to have been deeply influenced by two women besides his mother: he says that Diotima, a witch and priestess from Mantinea, taught him all he knows about eros, or love; and that Aspasia, the mistress of Pericles, taught him the art of rhetoric.[33] John Burnet argued that his principal teacher was the Anaxagorean Archelaus but his ideas were as Plato described them; Eric A. Havelock, on the other hand, considered Socrates' association with the Anaxagoreans to be evidence of Plato's philosophical separation from Socrates.
Socratic paradoxes
Many of the beliefs traditionally attributed to the historical Socrates have been characterized as "paradoxical" because they seem to conflict with common sense. The following are among the so-called Socratic Paradoxes:[34] * No one desires evil. * No one errs or does wrong willingly or knowingly. * Virtue—all virtue—is knowledge. * Virtue is sufficient for happiness.
The term, "Socratic paradox" can also refer to a self-referential paradox, originating in Socrates' utterance, "what I do not know I do not think I know",[35] often paraphrased as "I know that I know nothing."
Knowledge
One of the best known sayings of Socrates is "what I do not know I do not think I know". The conventional interpretation of this remark is that Socrates' wisdom was limited to an awareness of his own ignorance. Socrates believed wrongdoing was a consequence of ignorance and those who did wrong knew no better. The one thing Socrates consistently claimed to have knowledge of was "the art of love", which he connected with the concept of "the love of wisdom", i.e., philosophy. He never actually claimed to be wise, only to understand the path a lover of wisdom must take in pursuing it. It is debatable whether Socrates believed humans (as opposed to gods like Apollo) could actually become wise. On the one hand, he drew a clear line between human ignorance and ideal knowledge; on the other, Plato's Symposium (Diotima's Speech) and Republic (Allegory of the Cave) describe a method for ascending to wisdom.
In Plato's Theaetetus (150a), Socrates compares himself to a true matchmaker (προμνηστικός promnestikós), as distinguished from a panderer (προᾰγωγός proagogos). This distinction is echoed in Xenophon's Symposium (3.20), when Socrates jokes about his certainty of being able to make a fortune, if he chose to practice the art of pandering. For his part as a philosophical interlocutor, he leads his respondent to a clearer conception of wisdom, although he claims he is not himself a teacher (Apology). His role, he claims, is more properly to be understood as analogous to a midwife (μαῖα maia). Socrates explains that he is himself barren of theories, but knows how to bring the theories of others to birth and determine whether they are worthy or mere "wind eggs" (ἀνεμιαῖον anemiaion). Perhaps significantly, he points out that midwives are barren due to age, and women who have never given birth are unable to become midwives; they would have no experience or knowledge of birth and would be unable to separate the worthy infants from those that should be left on the hillside to be exposed. To judge this, the midwife must have experience and knowledge of what she is judging.
Virtue
Socrates believed the best way for people to live was to focus on the pursuit of virtue rather than the pursuit, for instance, of material wealth.[36] He always invited others to try to concentrate more on friendships and a sense of true community, for Socrates felt this was the best way for people to grow together as a populace.[37] His actions lived up to this: in the end, Socrates accepted his death sentence when most thought he would simply leave Athens, as he felt he could not run away from or go against the will of his community; as mentioned above, his reputation for valor on the battlefield was without reproach.
The idea that there are certain virtues formed a common thread in Socrates' teachings. These virtues represented the most important qualities for a person to have, foremost of which were the philosophical or intellectual virtues. Socrates stressed that "the unexamined life is not worth living [and] ethical virtue is the only thing that matters."

B. PLATO
Metaphysics
"Platonism" is a term coined by scholars to refer to the intellectual consequences of denying, as Plato's Socrates often does, the reality of the material world. In several dialogues, most notably the Republic, Socrates inverts the common man's intuition about what is knowable and what is real. While most people take the objects of their senses to be real if anything is, Socrates is contemptuous of people who think that something has to be graspable in the hands to be real. In the Theaetetus, he says such people are "eu a-mousoi", an expression that means literally, "happily without the muses" (Theaetetus 156a). In other words, such people live without the divine inspiration that gives him, and people like him, access to higher insights about reality.
Socrates's idea that reality is unavailable to those who use their senses is what puts him at odds with the common man, and with common sense. Socrates says that he who sees with his eyes is blind, and this idea is most famously captured in his allegory of the cave, and more explicitly in his description of the divided line. The allegory of the cave (beginsRepublic 7.514a) is a paradoxical analogy wherein Socrates argues that the invisible world is the most intelligible ("noeton") and that the visible world ("(h)oraton") is the least knowable, and the most obscure.
Socrates says in the Republic that people who take the sun-lit world of the senses to be good and real are living pitifully in a den of evil and ignorance. Socrates admits that few climb out of the den, or cave of ignorance, and those who do, not only have a terrible struggle to attain the heights, but when they go back down for a visit or to help other people up, they find themselves objects of scorn and ridicule.
According to Socrates, physical objects and physical events are "shadows" of their ideal or perfect forms, and exist only to the extent that they instantiate the perfect versions of themselves. Just as shadows are temporary, inconsequential epiphenomena produced by physical objects, physical objects are themselves fleeting phenomena caused by more substantial causes, the ideals of which they are mere instances. For example, Socrates thinks that perfect justice exists (although it is not clear where) and his own trial would be a cheap copy of it.
The allegory of the cave (often said by scholars to represent Plato's own epistemology and metaphysics) is intimately connected to his political ideology (often said to also be Plato's own), that only people who have climbed out of the cave and cast their eyes on a vision of goodness are fit to rule. Socrates claims that the enlightened men of society must be forced from their divine contemplations and be compelled to run the city according to their lofty insights. Thus is born the idea of the "philosopher-king", the wise person who accepts the power thrust upon him by the people who are wise enough to choose a good master. This is the main thesis of Socrates in the Republic, that the most wisdom the masses can muster is the wise choice of a ruler.
Epistemology
Many have interpreted Plato as stating—even having been the first to write—that knowledge is justified true belief, an influential view that informed future developments in epistemology.[42] This interpretation is partly based on a reading of the Theaetetus wherein Plato argues that knowledge is distinguished from mere true belief by the knower having an "account" of the object of her or his true belief (Theaetetus 201c–d). And this theory may again be seen in the Meno, where it is suggested that true belief can be raised to the level of knowledge if it is bound with an account as to the question of "why" the object of the true belief is so (Meno 97d–98a).[43] Many years later, Edmund Gettierfamously demonstrated the problems of the justified true belief account of knowledge. That the modern theory of justified true belief as knowledge which Gettier addresses is equivalent to Plato's is accepted by some scholars but rejected by others.[44] Plato himself also identified problems with the justified true belief definition in the Theaetetus, concluding that justification (or an "account") would require knowledge of differentness, meaning that the definition of knowledge is circular (Theaetetus 210a–b).[45]
Later in the Meno, Socrates uses a geometrical example to expound Plato's view that knowledge in this latter sense is acquired by recollection. Socrates elicits a fact concerning a geometrical construction from a slave boy, who could not have otherwise known the fact (due to the slave boy's lack of education). The knowledge must be present, Socrates concludes, in an eternal, non-experiential form.
In other dialogues, the Sophist, Statesman, Republic, and the Parmenides, Plato himself associates knowledge with the apprehension of unchanging Forms and their relationships to one another (which he calls "expertise" in Dialectic), including through the processes of collection and division.[46] More explicitly, Plato himself argues in the Timaeus that knowledge is always proportionate to the realm from which it is gained. In other words, if one derives one's account of something experientially, because the world of sense is in flux, the views therein attained will be mere opinions. And opinions are characterized by a lack of necessity and stability. On the other hand, if one derives one's account of something by way of the non-sensible forms, because these forms are unchanging, so too is the account derived from them. That apprehension of forms is required for knowledge may be taken to cohere with Plato's theory in the Theaetetus and Meno. Indeed, the apprehension of Forms may be at the base of the "account" required for justification, in that it offers foundational knowledge which itself needs no account, thereby avoiding an infinite regression.

C. ARISTOTLE
Ethics
Aristotle considered ethics to be a practical rather than theoretical study, i.e., one aimed at becoming good and doing good rather than knowing for its own sake. He wrote several treatises on ethics, including most notably, the Nicomachean Ethics.
Aristotle taught that virtue has to do with the proper function (ergon) of a thing. An eye is only a good eye in so much as it can see, because the proper function of an eye is sight. Aristotle reasoned that humans must have a function specific to humans, and that this function must be an activity of the psuchē (normally translated as soul) in accordance with reason (logos). Aristotle identified such an optimum activity of the soul as the aim of all human deliberate action, eudaimonia, generally translated as "happiness" or sometimes "well being". To have the potential of ever being happy in this way necessarily requires a good character (ēthikē aretē), often translated as moral (or ethical) virtue (or excellence).
Aristotle taught that to achieve a virtuous and potentially happy character requires a first stage of having the fortune to be habituated not deliberately, but by teachers, and experience, leading to a later stage in which one consciously chooses to do the best things. When the best people come to live life this way their practical wisdom (phronesis) and their intellect (nous) can develop with each other towards the highest possible human virtue, the wisdom of an accomplished theoretical or speculative thinker, or in other words, a philosopher.

D. IMMANUEL KANT
Categories of the Faculty of Understanding
In studying the work of Kant one must realize that there is a distinction between "understanding" as the general concept (in German, das Verstehen) and the "understanding" as a faculty of the human mind (in German, der Verstand, "the intellect"). In much English language scholarship, the word "understanding" is used in both senses.
Kant deemed it obvious that we have some objective knowledge of the world, such as, say, Newtonian physics. But this knowledge relies onsynthetic, a priori laws of nature, like causality and substance. The problem, then, is how this is possible. Kant's solution was to reason that the subject must supply laws that make experience of objects possible, and that these laws are the synthetic, a priori laws of nature that we know apply to all objects before we experience them. So, to deduce all these laws, Kant examined experience in general, dissecting in it what is supplied by the mind from what is supplied by the given intuitions. What has just been explicated is commonly called a transcendental reduction.[41]
To begin with, Kant's distinction between the a posteriori being contingent and particular knowledge, and the a priori being universal and necessary knowledge, must be kept in mind. For if we merely connect two intuitions together in a perceiving subject, the knowledge is always subjective because it is derived a posteriori, when what is desired is for the knowledge to be objective, that is, for the two intuitions to refer to the object and hold good of it necessarily universally for anyone at anytime, not just the perceiving subject in its current condition. What else is equivalent to objective knowledge besides the a priori, that is to say, universal and necessary knowledge? Nothing else, and hence before knowledge can be objective, it must be incorporated under an a priori category of the understanding.[41][42]
For example, say a subject says, "The sun shines on the stone; the stone grows warm," which is all he perceives in perception. His judgment is contingent and holds no necessity. But if he says, "The sunshine causes the stone to warm," he subsumes the perception under the category of causality, which is not found in the perception, and necessarily synthesizes the concept sunshine with the concept heat, producing a necessarily universally true judgment.[41]
To explain the categories in more detail, they are the preconditions of the construction of objects in the mind. Indeed, to even think of the sun and stone presupposes the category of subsistence, that is, substance. For the categories synthesize the random data of the sensory manifold into intelligible objects. This means that the categories are also the most abstract things one can say of any object whatsoever, and hence one can have an a priori cognition of the totality of all objects of experience if one can list all of them. To do so, Kant formulates another transcendental deduction.[41]
Judgments are, for Kant, the preconditions of any thought. Man thinks via judgments, so all possible judgments must be listed and the perceptions connected within them put aside, so as to make it possible to examine the moments when the understanding is engaged in constructing judgments. For the categories are equivalent to these moments, in that they are concepts of intuitions in general, so far as they are determined by these moments universally and necessarily. Thus by listing all the moments, one can deduce from them all of the categories.[41]
One may now ask: How many possible judgments are there? Kant believed that all the possible propositions within Aristotle's syllogistic logic are equivalent to all possible judgments, and that all the logical operators within the propositions are equivalent to the moments of the understanding within judgments. Thus he listed Aristotle's system in four groups of three: quantity (universal, particular, singular), quality (affirmative, negative, infinite), relation (categorical, hypothetical, disjunctive) and modality (problematic, assertoric, apodeictic). The parallelism with Kant's categories is obvious: quantity (unity, plurality, totality), quality (reality, negation, limitation), relation (substance, cause, community) and modality (possibility, existence, necessity).[41]
The fundamental building blocks of experience, i.e. objective knowledge, are now in place. First there is the sensibility, which supplies the mind with intuitions, and then there is the understanding, which produces judgments of these intuitions and can subsume them under categories. These categories lift the intuitions up out of the subject's current state of consciousness and place them within consciousness in general, producing universally necessary knowledge. For the categories are innate in any rational being, so any intuition thought within a category in one mind is necessarily subsumed and understood identically in any mind. In other words we filter what we see and hear.[41]
Schema
Kant ran into a problem with his theory that the mind plays a part in producing objective knowledge. Intuitions and categories are entirely disparate, so how can they interact? Kant's solution is the schema: a priori principles by which the transcendental imagination connects concepts with intuitions through time. All the principles are temporally bound, for if a concept is purely a priori, as the categories are, then they must apply for all times. Hence there are principles such as substance is that which endures through time, and the cause must always be prior to the effect.
Moral philosophy
Kant developed his moral philosophy in three works: Groundwork of the Metaphysic of Morals (1785),[45] Critique of Practical Reason(1788), and Metaphysics of Morals (1797).
In the Groundwork, Kant's method involves trying to convert our everyday, obvious, rational[46] knowledge of morality into philosophical knowledge. The latter two works followed a method of using "practical reason", which is based only upon things about which reason can tell us, and not deriving any principles from experience, to reach conclusions which are able to be applied to the world of experience (in the second part of The Metaphysic of Morals).
Kant is known for his theory that there is a single moral obligation, which he called the "Categorical Imperative", and is derived from the concept of duty. Kant defines the demands of the moral law as "categorical imperatives". Categorical imperatives are principles that are intrinsically valid; they are good in and of themselves; they must be obeyed by all, in all situations and circumstances, if our behavior is to observe the moral law. It is from the Categorical Imperative that all other moral obligations are generated, and by which all moral obligations can be tested. Kant also stated that the moral means and ends can be applied to the categorical imperative, that rational beings can pursue certain "ends" using the appropriate "means". Ends that are based on physical needs or wants always give merely hypothetical imperatives. The categorical imperative, however, may be based only on something that is an "end in itself". That is, an end that is a means only to itself and not to some other need, desire, or purpose.[47] He believed that the moral law is a principle of reasonitself, and is not based on contingent facts about the world, such as what would make us happy, but to act upon the moral law which has no other motive than "worthiness of being happy".[48] Accordingly, he believed that moral obligation applies only to rational agents.[49]
A categorical imperative is an unconditional obligation; that is, it has the force of an obligation regardless of our will or desires (Contrast this with hypothetical imperative)[50] InGroundwork of the Metaphysic of Morals (1785) Kant enumerated three formulations of the categorical imperative that he believed to be roughly equivalent.[51]
Kant believed that if an action is not done with the motive of duty, then it is without moral value. He thought that every action should have pure intention behind it; otherwise it was meaningless. He did not necessarily believe that the final result was the most important aspect of an action, but that how the person felt while carrying out the action was the time at which value was set to the result.
In Groundwork of the Metaphysic of Morals, Kant also posited the "counter-utilitarian idea that there is a difference between preferences and values and that considerations of individual rights temper calculations of aggregate utility", a concept that is an axiom in economics:[52]
Everything has either a price or a dignity. Whatever has a price can be replaced by something else as its equivalent; on the other hand, whatever is above all price, and therefore admits of no equivalent, has a dignity. But that which constitutes the condition under which alone something can be an end in itself does not have mere relative worth, i.e., price, but an intrinsic worth, i.e., a dignity. (p. 53, italics in original).
A phrase quoted by Kant, which is used to summarize the counter-utilitarian nature of his moral philosophy, is Fiat justitia, pereat mundus, ("Let justice be done, though the world perish"), which he translates loosely as "Let justice reign even if all the rascals in the world should perish from it". This appears in his 1795 Perpetual Peace (Zum ewigen Frieden. Ein philosophischer Entwurf.), Appendix 1.