Teleological (or consequentialist) theories of ethics (e.g., egoism, hedonism, utilitarianism) assume that the first task of ethics is to determine that which has value (and thus defines the good) and then to indicate how we are obligated to do what is valuable.  Before we know why we should do good, we first have to determine what the good is.  Specifically, we have to consider the consequences of our actions, since actions in themselves are neither good nor bad.

• Hedonism: every human action is motivated by the pursuit of pleasure (psychological hedonism) or ought to be motivated by the pursuit of pleasure (moral hedonism).  (Note that moral hedonism presumes that it is possible not to be motivated by the pursuit of pleasure, but that it is unwise to do so.)

• Epicurus: one always ought to do the good, and the good is that which is pleasurable.  Some pleasures result from satisfying natural desires--some of which are necessary (like the desires for food and sleep), some of which are unnecessary and often have pains associated with them (like the desire for sex).  Other pleasures result from satisfying vain desires, desires not easy to satisfy and often lead to pain.
According to Epicurus, we should pursue those things that are pleasurable without also having pains associated with them.  Thus we should try to develop values for beauty, prudence, honor, justice, courage, and honesty rather than so-called "epicurean" sensualism because such sensualism is always mixed with pains.  One's pleasures always should be moderated: real pleasure is the absence of pain.

• Utilitarianism: social hedonism; the good is what produces the greatest amount of happiness for the greatest number of people (including oneself), even if it causes unhappiness to oneself.

• Jeremy Bentham: people should do what produces pleasure, considering the intensity, duration, certainty, quickness, how many other pleasures are produced, freedom from pains, and the number of people affected.  Every person's happiness, no matter how mundane or qualitatively inferior, is given equal weight: democracy permits allowing standards to fall to the lowest common denominator.  Pleasure and pain dictate all human behavior.
Objections:
• It is simply not true that pleasure and pain dictate all human behavior
• How does one make hedonistic calculations?  Is there a standard that all can agree on?
• What about qualities of pleasures?
• The calculation surely must not be aimed at the greatest absolute happiness, but the greatest average happiness.  Otherwise, the minority's rights (and happiness) might be ignored
• J. S. Mill: the quality of pleasures needs to be considered in addition to the quantity of pleasure.  Some kinds of pleasure are more desirable and more valuable (for social, cultural reasons) than others.  Even though lower pleasures are often more immediate, intense, etc., they are not as valuable as higher pleasures.  The quality of pleasures is determined by those who are familiar with both and who prefer one to the other, regardless of any feeling of moral obligation.  What makes one pleasure more desirable is that it is in fact more desired by "competent judges of cultivation."  It is therefore better to be "Socrates dissatisfied than a pig satisfied."

Objections:
 

• This sounds elitist.
• If some pleasures should not be encouraged, not all pleasures are good (good is thus not simply the same as pleasure or that which produces happiness).
• If some pleasures are more valuable than others, there must be a criterion for such a determination (e.g., human fulfillment or well-being) which is pleasurable only indirectly.
Problems with Utilitarianism in general:
 
• Injustice: if the total amount of happiness is increased by violating the rights of a few, then utilitarianism seems to condone unjust acts (act utilitarianism).  But if such acts were to become the rule, there would be less happiness.  So, according to rule utilitarianism, we should do only what produces the greatest amount of happiness if it is done generally or as a rule.
• But what if following the rule would yield worse consequences than violating the rule?  If we depend on consequences to make moral judgments, shouldn't we violate the rule?--in which case, what is the point of having an ethical theory?

• As the 17th-century thinker Baruch Spinoza argues, everything in nature is part of God; indeed, nature is God.  To accept the fact that all things are one is to embrace or love God.  When we no longer see the world solely from our own perspective, we should accept everything as valuable in itself--not as something we can exploit, for that would be to claim (unjustifiably) that we are more important than anything else in nature.