Legal positivism is the incoherent idea that laws can be separated from truth, metaphysics, ontology and morality. Instead, law is simply the arbitrary whims of those in power. As Zippy Catholic explains, positivism in law suffers from the same incoherence as positivism in religion:
Positivism in religion – sola scriptura – has resulted in religion being whatever the individual interpreting the Bible says it is. It has resulted in more than ten thousand different Christian or pseudo-Christian religions. And positivism in law has the same effect. What many conservatives don’t appreciate is that positivism and postmodernism are not opposed to each other but are directly connected faces of the same underlying basic irrationality; an irrationality that results in license to ignore the natural law.
Fundamentally, this incoherence results from the very nature of government. Necessarily, government must resolve controvertible issues according to some conception of the good and use its authority and power to do so. A proper conception of the good cannot be separated from metaphysics, ontology, morality, theology and the Truth. When liberals claim “neutrality”, the resulting politics is not neutral, for neutrality is impossible, but instead begs the question in favor of a liberal conception of the good. The nature of liberalism comes bundled with its own metaphysical presuppositions. The recent court discussion centered around so called ‘gay marriage’ is a prime example of this presupposition.
The particular case is expected to settle the question of whether a privately owned business can refuse services to potential customers based on religious convictions. Some of the arguments compared “same-sex marriage” to interracial marriage or to a private business denying service to a specific racial group. Both analogies are seriously flawed.
The reason the analogies with race break down is because the issue isn't about denying service to a particular group of people, but rather not being forced to formally and materially cooperate in something that is both ontologically and morally false. There are obviously first amendment reasons why this is being presented as a soley religious issue, but in reality this is a question of ontology and truth.
Ontology is the branch of metaphysics that deals with the nature of being. Prior to the moral and religious convictions regarding homosexuality and same-sex unions, is the ontological question of what is sex and what is marriage. Once the nature of sex and marriage are understood, it becomes apparent that both “gay sex” and “same-sex marriage” are contradictory.
In order to understand the ontology of sex and marriage, we first must understand the natural law. Here is Edward Feser explaining the natural law specifically with sex:
Since it’s the natural law theory example that critics of the theory always get the most worked up over, let’s look at sex. One way to understand the traditional natural law view of the matter is this. If you consider the sexual drives that human beings have, then it is blindingly obvious that if those drives have any natural purpose at all – if they were, say, designed with a certain end in view – then that purpose is to get people to use their sexual organs. And if you consider the sexual organs themselves, then it is also blindingly obvious that if they were designed with any purpose in mind, then that purpose is procreation. More specifically, the purpose of a penis – again, if you assume that it was indeed designed with a purpose in mind – is quite obviously to deposit semen into a vagina (and also, of course, to urinate). That’s what it’s for, if indeed it is for anything, and whether or not it can be used for other purposes.
The reason it is contradictory to speak of “gay sex” is because sex is the union of the male and female sex organs. Any kind of same-sex “sexual” behavior is thus a perversion or imitation of sex, particularly sodomy and fellatio. It is impossible for two members of the same sex to have sex with each other. The nature of sex is fundamentally related to the nature of marriage.
Marriage is a particular kind of relationship that differs fundamentally from all other kinds of relationships. For example, a sibling relationship is a relationship among persons sharing the same parents and just as a parent/offspring relationship differs fundamentally from a sibling relationship so to does a marriage fundamentally differ from a relationship between two members of the same sex. Marriage, by its nature, is the potential procreative union between one man and one woman. This potential is obviously lacking in same-sex relationships. Furthermore, this procreative union results in the creation of the family and with it the obligation of parents to raise their own children and cultivate virtue within them. As Aristotle observed, the first partnerships among human beings are between “persons who cannot exist without one another”. This partnership is one male and one female in the Sacrament of Marriage. From this partnership families are born and from families, villages and from villages, nations. Contrary to liberalism, the family is the fundamental political unit.
The most prominent objection to marriage is that not all marriages result in children; some couples will choose not to procreate and some couples for medical reasons simply cannot. And this is where it becomes necessary to talk about metaphysics. When we are speaking about a potential procreative union, we are speaking about the kind or essence of that relationship and the individuals involved. For example, we would speak of a bat as a kind of mammal that flies, but this does not mean that every individual bat will fly. Some bats may not be able to fly due to injury, but this simply does not change the nature or essence of a bat as a flying mammal. Bats, by their nature, have the potential to fly even if not every bat actualizes that potential. Likewise, the sexual union of male and female has by its nature the potential for procreation even if not every union actualizes that potential. Thus it isn't the case that a same-sex union simply does not actualize a potential, but on the other hand, that a same-sex union has no such potential.
The liberal and conservative world views are incompatible. Not only do they differ on policy, but on metaphysics, epistemology, ethics and theology. For far too long conservatives have simply accepted the implicit metaphysical claims of the liberal establishment. It's time to tackle this issue head on, most importantly because the liberal world view is false.