Strengths and Weaknesses of Natural Law

A table on the strength and weaknesses on Natural Law:
Autonomous and rational

Natural law is an autonomous, rational theory and it is wrong to say that you have to believe in God to make sense of it. Aquinas speaks of “the pattern of life lived according to reason.” You could be a Darwinian atheist and believe in natural law derived by empirical observation, with the primary precept of survival (Aquinas’ preservation of life). Dawkins go so far as to argue for a natural genetic tendency to be altruistic: a lust to be nice.

“The theory of Natural Law suggests..morality is autonomous. It has its own questions, its own methods of answering them, and its own standards of truth … religious considerations are not the point.” Rachels (2006:56)

A Fixed Human Nature

Aquinas believes in one fixed, shared human nature with certain natural properties eg heterosexual. But evidence suggests there are gay genes and so there is no one natural human nature, but many. This is actually a form of the naturalistic fallacy , the movement from an “is” to an “ought.”

“It may be that sex does produce babies, but it does not follow that sex ought or ought not to be engaged in only for that purpose. Facts are one thing, values are another.”

Rachels (2006:52)

An exalted view of human beings

Humans are capable of using their reason to work out how to live. So we are not slaves to our passions or our genes. Natural Law has a purpose: a flourishing society and a person fulfilled and happy. It is not ultimately about restricting us by rules, but setting us free to fulfil our proper purpose, inherent in our design: to rationally assent to personal growth. If we can agree on our purpose we can agree on what morality is for. Moreover, we don’t have to accept the fact/value division inherent in GE Moore or AJ Ayer’s philosophy.

“The natural world is not to be regarded merely as a realm of facts, devoid of value or purpose. Instead, the world is conceived to be a rational order with value and purpose built into its very nature.”Rachels 2006: 50

An optimistic view

Aquinas believes that we innately (we are born with) have a “tendency to do good and avoid evil,” which he calls the synderesis rule . This is in contrast with Augustine who believes that, due to the Fall, we are born into sin, the sin of Adam, or perhaps the view of psychologists like Freud, that natural selfishness becomes moralised by upbringing and socialisation.

This is clearly an optimistic view given human beings propensity to destroy life in war, exploit other sentient creatures for our own ends, misuse sex, indulge in antisocial behaviour, and prefer the X box 360 to education.


Again, it’s a misunderstanding to think of Natural Law as inflexible. The primary precepts may be general and unchanging, but as Aquinas himself argued, secondary precepts (the application of primary precepts which create the apparent absolute rules of Natural law) can change depending on circumstances, culture and worldview.

The Doctrine of Double Effect is also a way to escape the moral dilemmas which exist when two rules conflict. (See Pojman pgs 47-51)

Immoral outcomes

Natural Law has been interpreted to ban contraception, because this interferes with the natural primary precept of reproduction. But a. it’s not clear that sex is exclusively for reproduction, in fact, the function of bonding may be primary and b. the consequence of this policy in Africa has had evil effects of the spread of AIDS and the birth of AIDS infected children who often become orphans living on the streets.







Past Questions

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