This has been summarised from a very useful clear overview of moral theory and using Ethics the Heart of Health Care – 2nd Edition – David Seedhouse

The term ‘ethics’ broadly describes the way in which we look at and understand life, in terms of good and bad or right and wrong. Moral theories are the frameworks we use to justify or clarify our position when we ask ourselves "what should I do in this situation?" or "what is right or wrong for me?" – There are many of these moral theories – important examples are:

  • Deontology - Deontology or Kantianism is an obligation-based theory whose chief author was Immanuel Kant, who lived in the 18th century. This theory emphasises the type of action rather than the consequences of that action. Deontologists believe that moral decisions should be made based on one’s duties and the rights of others. According to Kant, morality is based on pure reason. As people have the innate ability to act rationally, they therefore must act morally, irrespective of personal desires. Another way of stating Kant’s theory is "Act morally regardless of the consequences."
  • Consequentialism - In consequentialism, the consequence of an action justifies the moral acceptability of the means taken to reach that end. The results of actions outweigh any other consideration; in other words, ‘the end justifies the means.’
  • Utilitarianism - Jeremy Bentham was an early and influential advocate of utilitarianism, the dominant consequentialist position. A utilitarian believes in ‘the greatest happiness for the greatest number.’ The more people who benefit from a particular action, the greater its good.
  • The four principles approach

No one right or wrong theory. They all merge and borrow from each other at times