Natural law creates a rational basis for determination of positive law and also a criteria for individuals to decide whether to obey the positive law or not. Laws may be unjust also. But, he says that the circumstance may demand that an unjust law be follwed as disobedience leads to weakening the legal system. This applies more to judges.
The positivist critique that by saying that natural law to derives an ought from an is. Finnis says it is not derived from anything but are self-evident. .
Criticism:.
1. So, the question is according to whose point of view any concept of reason is formulated. The concept of reason will be affected by histories. (finnis thinks that natural law has no history, it is eternal and unchanging) what is good, bad or reason is shaped through historical factors and has changed over centuries. Eg: reason as a concept has reflected norms which are socially male, Eurocentric and white. So we need to be aware of the differences in power when modeling "reason". So, what counts as reasonable might be suppressive and render illegitimate other notions of reason.
2. Author finds a problem in finnis defining religion as a higher order above man and woman and thinking about it is necessary to achieve human freedom. This order is transcendental, even if not divine. Authoer says that for freedom and interpersonal relationships things to be thought about are patriarchy, racism, heteronormativity, capitalism.and the higher order can be science, philosophy etc.
3. The Author then says that how does finis know this is what basic? And what becomes problematic is the conclusions that we derive from these basic goods.
4. Also, good depend on ones experience. Same sex relationship for finnis is a violation of natural law as he would argue that any perception of good attached to them is not self-evident and natural but is derived from natural law of the society. What is the nature of self-evidence.