The Kantian Golden Rule and the universalizability test function like ‘utilitarianism’ in the sense that they require one to imagine if it has positive and negative outcomes. For instance, Kant’s argument against ‘theft’ is ‘utilitarian’ in the sense that the absence of property will decrease prosperity.
Rothbard also incorporated an ‘universalizability test’ for free exchange based on the ‘utilitarian’ argument that trade restrictions will create decreased prosperity of society.
Deontological ethics is a form of consequentialism in the sense that we can define an ‘inherently good act’ as a ‘good consequence’ and an ‘inherently bad act’ as a ‘bad consequence’.
Contrastingly, ‘rule-consequentialism’ is indistinguishable from some forms of ‘deontology’. Most '‘consequentialists’ are de facto ‘deontologists’ in the sense that they will respect moral prescriptions such as “don’t steal” and “don’t murder.” Most ‘deontologists’ are not ‘absolutists’ in the sense that they will not always apply their prescriptions in lifeboat situations.
According to the above meanings, ‘deontology’ and ‘consequentialism’ distinction is a false dichotomy.
In fact, we have seen many debates within the so-called ‘deontological libertarians’ and the so-called ‘consequentialist libertarians’ that confuses their terminology. For example, some self-identified ‘consequentialist libertarians’ conflate ‘deontological libertarianism’ with ‘moral absolutism’, which in fact that deontology is not inherently ‘absolutist’ in enforcing moral prescriptions. Some self-identified ‘deontological libertarians’ define ‘consequentialist libertarianism’ as a form of ‘moral relativism’ in which it allows ‘whatever it goes to maximize some group of individuals’. However, most self-identified ‘consequentialist libertarians’ disallow theft at all contexts (except lifeboat situations) just like that most self-identified ‘deontological libertarians’ disallow theft at all contexts (except perhaps lifeboat situations). The so-called ‘controversy’ is primarily based on the different definitions of ‘deontology’ and ‘consequentialism’.
To clarify, we do not think that the controversy is purely semantic. We just think that the terms ‘consequentialism’ and ‘deontology’ are so ambiguous that we should not use them without clarification. See our above conclusion that ‘deontology’ and ‘consequentialism’ in their broad senses are indistinguishable.
However, Austrian economists usually define “utilitarianism” as an ethical doctrine which enables technocrats or rulers to intervene economically and make utility calculations. They define “utilitarianism” as socialism which makes cardinal utility calculations.
Broadly speaking, however, Rothbardian ‘natural law’ and the categorical imperative are a forms of ‘utilitarianism’ in the sense that it applies the universalizability tests to the free market and free exchange. Rothbard even discusses the maximization of ‘psychic utility’ (or ‘profit’). Most self-identified ‘utilitarians’ will agree that ethics which maximizes ‘psychic utility’ is a form of ‘utilitarianism’. However, Rothbard has a knee-jerk reaction against the term ‘utilitarianism’ because he conflates ‘utilitarianism’ roughly with ‘socialism’.