Ethics is the struggle to determine what is right or wrong, or lsquo good rsquo and lsquo bad rsquo. Some ethical theories are hedonistic ndash they say that pleasure and the absence of pain are the only ultimately lsquo good rsquo ends towards which to aim. Some christian ethicists argue that following god rsquo s will ndash as revealed through prayer, scriptures and prophecy ndash is the ultimate good. The theory of natural law was put forward by aristotle but championed by thomas aquinas 1225 74.

Man desires happiness, but for aquinas this means fulfilling our purpose as humans. He said, in summa theologica, whatever man desires, he desires it under the aspect of good. We will see that aquinas first asks what our human nature is, and then looks at the rules that can be derived from this. the purpose of humans the primary precepts there is a single guiding principle that sums up our nature: good is to be done and pursued, and evil is to be avoided. Aquinas looks at what is 'good' for humans, saying that humans share part of their nature with all natural things, part with animals, and part of our human nature is particular to us. Aquinas said: inasmuch as every substance seeks the preservation of its own being.

And of warding off its obstacles, belongs to the natural law those things are said to belong to the natural law, which nature has taught to all animals pandect. I , such as sexual intercourse, education of offspring and so forth man has a natural inclination to know the truth about god, and to live in society although textbooks talk of five primary precepts, and some resources on this site reflect this, bernard hoose revealed, over lunch at an ethics conference, his frustration with this tendency. Read summa theologica yourself, and you may feel that aquinas is not giving an exhaustive list, but simply some examples of self evident principles perceived by reason. A mnemonic for these might be pregs: in 1930, cd broad contrasted teleology and deontology in an attempt to categorise ethical theories. By teleology, he meant theories where the rightness or wrongness of an action is always determined by its tendency to produce consequences which are intrinsically good or bad. According to broad, deontological theories hold that such and such a kind of action would always be right or wrong in such and such circumstances, no matter what its consequences might be. In essence, teleology is concerned with good and bad, deontology with right and wrong.

This distinction, and these definitions, are seen by many ethicists as unhelpful, but they are on most syllabuses. Broad admitted that most theories are actually mixed , and we can see this in natural law. In defining the primary precepts, aquinas was stating 'self evident principles' that are universal and absolute they are part of our very nature as humans. However, looking at aristotle's notion of telos as excellence, we see that the primary precepts are not concerned with actions themselves, but with our telos or purpose. For aquinas, man's final purpose telos is happiness with god beatitudo , something for which we all have an innate desire.

The primary precepts are our natural inclinations that guide us towards this final purpose. From the general principles, practical reason enables us to derive secondary precepts. They concern rules for our actions, for example goods entrusted to another should be restored to their owner.

If i am looking after your money, i should not give it away to a charity, even if doing so would bring about some good. However, this is not always an absolute duty, and this causes confusion in understanding natural law using the above example, aquinas says: it is right and true for all to act according to reason. And from this principle it follows as a proper conclusion, that goods entrusted to another should be restored to their owner. Now this is true for the majority of cases: but it may happen in a particular case that it would be injurious, and therefore unreasonable, to restore goods held in trust for instance, if they are claimed for the purpose of fighting against one's country. This doesn't mean that we do not have a duty to return goods entrusted to us, but that there may be conflicting duties that prevent us from doing so. Secondary precepts are rules derived from primary precepts using practical reason. In some cases, they refer to an action that is unnatural, and is therefore always wrong.

For example, aquinas felt that masturbation went against the natural end telos of sex, which is procreation. However, in modern infertility treatment, masturbation might be used to assist procreation through artificial insemination by a husband. On this issue, natural law theorists disagree about whether masturbation is unnatural, and therefore disagree about the secondary precept 'do not masturbate'. Aquinas gives examples in summa theologica as illustrations of those actions that are wrong in and of themselves because they contradict the primary precepts of natural law: theft lying fornicating committing adultery killing the innocent these are all examples of deonotological, absolutist secondary precepts derived from the self evident, universal teleological primary precepts. Some secondary precepts are deontological concerning actions rather than ends, and related to our specific duties , but not absolutist. lsquo efficient rsquo and lsquo final rsquo causes this is aristotle rsquo s distinction between what gets things done efficient cause and the end product final cause. With humans, it is the accomplishment of the end product that equates to lsquo good rsquo.

An example is sexuality ndash an efficient cause of sex is enjoyment: because humans enjoy sex, the species has survived through procreation. If we ask why people have sex, we might talk about attraction, psychological needs etc. The final cause is a matter of intent ndash what was god rsquo s purpose behind sex? the final cause assumes a rational mind behind creation, and as such moves from descriptive ethics saying what is there to normative ethics statements about what should or should not be the case. Another example ndash did the soldier shoot well? the efficient cause deals with the set of events around the shooting ndash did he aim well, was the shot effective, did the target die? these are descriptive points, and clearly don rsquo t tell us about the morality of the shooting. When we look into this area ndash was it right to kill? we are evaluating his intent, and are asking about the final cause.

We can then look at whether that cause is consistent with god rsquo s design for human beings. We may decide that killing innocent people goes against god rsquo s design for us, so it is always wrong to kill innocent people. As a result, natural law supports certain virtues prudence, justice, fortitude and temperance that allow the self to fulfil its purpose. Similarly there are many vices the seven deadly sins that must be avoided as they prevent the individual from being what god intended them to be.