Ethical frameworks are isomorphic

In principle, you can construct a utility function that represents a deontologist who abhors murder. You give a large negative value to the deontologist who commits murder. But it's kludgy. If a consequentialism talks about murder being bad, they mean that it's bad if anybody does it.

It is technically true that all of these ethical systems are equivalent, but saying which ethical system you use nonetheless carries a lot of meaning.

Instead, recognize that some ethical systems are better for some tasks.

If you choose your ethical system based on how it fulfils a task, you are already a consequentialist. Deontology and virtue ethics don't care about getting things done.

This reminds me of a part of Zombie Sequence, specifically the Giant Lookup Table. Yes, you can approximate consequentialism by a sufficiently complex set of deontological rules, but the question is: Where did those rules come from? What process generated them?

If we somehow wouldn't have any consequentialist intuitions, what is that probability that we would invent a "don't murder" deontological rule, instead of all the possible alternatives? Actually, why would we even feel a need for having any rules?

Deontological rules seem analogical to a lookup table. They are precomputed answers to ethical questions. Yes, they may be correct. Yes, using them is probably much faster than trying to compute them from scratch. But the reason why we have these deontological rules instead of some other deontological rules is partly consequentialism and partly historical accidents.

Previous discussion.

(ducks before accusations of misusing "isomorphic")

Old joke:

Q: Are these two objects isomorphic?

A: The first one is, but the second one isn't.

Can deontology and/or virtue ethics include "keep track of the effects of your actions, and if the results are going badly wrong, rethink your rules"?

Sort of! But not exactly. This is a topic I've been meaning to write a long post on for ages, and have given a few short impromptu presentations about.

Consequentialism, deontology, and virtue ethics are classifiers over world-histories, actions, and agents, respectively. They're mutually reducible, in that you can take a value system or a value-system fragment in any one of the three forms, and use it to generate a value system or value-system fragment in either of the other two forms. But value-system fragments are not equally naturally expressed in different forms; if you take a value from one and try to reframe it in the others, you sometimes get an explosion of complexity, particularly if you want to reduce value-system fragments which have weights and scaling properties, and have those weights and scaling properties carry through.

Henry Sidgwick in "The Methods of Ethics" actually makes the argument that Utilitarianism can be thought of as having a single predominant rule, namely the Greatest Happiness Principle, and that all other correct moral rules could follow from it, if you just looked closely enough at what a given rule was really saying. He noted that when properly expanded, a moral rule is essentially an injunction to act a certain way in a particular circumstance, that is universal to any person in identical circumstances. He also had some interesting things to say about the relationships between virtues and Utilitarianism, and more or less tried to show that the various commonly valued virtues could be inferred from a Utilitarian perspective.

Of course Sidgwick was arguing in a time before the clear-cut delineation of moral systems into "Deontological", "Consequentialist", and "Virtue Ethics". But I thought it would be useful to point out that early classical Utilitarian thinkers did not see these clear-cut delineations and instead, often made use of the language of rules and virtues to further their case for Utilitarianism as a comprehensive and inclusive moral theory.

I agree. In principle, you could construct a total order over all possible states of the world. All else is merely a pretty compression scheme. That being said, the scheme is quite necessary.

I don't believe the isomorphism holds under the (imo reasonable) assumption that rulesets and utility functions must be of finite length, correct?

I've been wondering if it makes sense to think of ethical philosophies as different classes of modeling assumptions:

Any moral statement can be expressed using the language of consequentialism, deontology or virtue ethics. The statements can therefore be translated from one framework to another. In that sense, the frameworks are equivalent. However, some statements are much easier to express in a given language.

Sometimes, we make models of ethics to explore the underlying rules that make an ethical statement "true". We try to predict whether an ethical statement is true using information from other, closely related ethical statements. However, ethical statements are multidimensional and therefore vary across many different axes. Two ethical statements can be closely related on one axis, and completely different from each other on another axis. In order to learn about the underlying rules, we have to specify which axis we are going to make modeling assumptions on. The choice will determine whether you call yourself a "consequentialist" or a "deontologist".

Problems such as "the repugnant conclusion" and "being so honest that you tell a murderer where your children are" occur when we extrapolate too far along this axis, and end up way beyond the range of problems that the model is fit to.

You can take a set of object-level answers and construct a variety of ethical systems that produce those answers, but it still matters which ethical system you use because your justification for those answers would be different, and because while the systems may agree on those answers, they may diverge on answers outside the initial set.

Isn't that a necessary step for the claims Derek Parfit makes about convergence in his "On What Matters"?

I have been saying this for quite some time. I regret not posting it first. It would be nice to have a more formal proof of all of this with utility functions, deontics and whatnot. If you are up for it, let me know. I could help, feedback, or we could work together. Perhaps someone else has done it already. It has always struck me as pretty obvious, but this is the first time I've seen stated like this.

I think the choice of systems is less important than their specifics, and that giving a choice but no specifics is being obtuse.

On isomorphism: every version of utilitarianism I know of leads to a repugnant conclusion of one way or another, or even multiple ones. I don't think that deontology and virtue ethics are nearly as susceptible. In other words, you cannot construct a utilitarian equivalent of an ethical system which is against suffering (without explicitly minimizing some negative utility) but does not value torture over dust specks.

EDIT: see the link in this lukeprog's comment. for limits of consequentialization.

(C)

All three theories are obviously wrong, moss-grown and vulnerable.

As consequentalist u can think that raping and killing is ok if torturer receives more amount of joy then amount of pain received by the victim. It seems even more obvious in the case with group of assaulters and one victim.

As deontologist you can always justify almost any deed by some trivial "for greater good" rule

And virtue ethics can be misleading in many ways, consider Halo effect and what can be consequences - Dr. Evil will take over world in seconds.

Please prove where I am wrong, I just pointed out weak points of each movement which seemed obvious to me