Usually people are thinking of ethical rules as "You must [not] X", where X is simple action that does not require any analysis, like "You must not lie".

But if X requires that, is it not a rule anymore? E.g. "You must try for best outcome" is not a rule? What is it then?

I'm asking this because I can't see the distinction between deontology and consequentialism (assuming "You must try for best outcome" is a rule) or virtue ethics. I'm rather seeing (consequentialism ∪ virtue ethics) ⊂ deontology.

  • See Deontic Logic as well as The Logic of Action. Commented Mar 29, 2018 at 12:35
  • A quick comment here: what you are talking about is "the exception that confirms the rule". Example: "You will be excepted from murder charges if you have willingly killed someone in the special case where it was necessary to protect yourself from being murdered yourself". This exception could not exist if there was not a rule "Thou shalt do no murder"; there can be no exception if there is no rule to seek exception from. So exceptions can confirm a moral rule.
    – MichaelK
    Commented Mar 29, 2018 at 12:37
  • @MichaelK, but in mathematics exception means that some rules are incorrect but other rules can exist that would be correct. Why shouldn't that apply to ethics?
    – rus9384
    Commented Mar 29, 2018 at 12:43
  • @rus9384: Rules can be heuristic, ethical, computational,... The rules in mathematics are a very special case of computational/methodological rules.
    – Philip Klöcking
    Commented Mar 29, 2018 at 12:45
  • 2
    What "lying" or "killing" are requires plenty of analysis, as court cases and ethical debates indicate. Any imperative has descriptive content, indeed is a declarative with "make it (not) happen" attached. The idea that ethics can be mathematized is a fantasy, and if our inability to mathematize something led to nihilism we'd be nihilists about almost everything. Deontic rules have to be definitive enough to be followed in most (not all) practical situations, "optimality" and "best outcome" are too vague for that, they are mostly meta-ethical heuristics to motivate more specific rules.
    – Conifold
    Commented Mar 29, 2018 at 20:40

1 Answer 1


1 Ethical rules need not be simple. They can be loaded with complexity. All they need is a ground, a moral property, and universality :

For every x, if Gx, then Mx : in every situation in which you are life-threateningly attacked [ground], in that that situation retaliate in self-defence [moral property].

Now that is a simple rule (not one I'm sure I'd accept) but it's clear from the logical form of a rule, just outlined, that the ground could be a monster conjunction and the moral property extremely complex. (I outline a modified logical form in 3 but it does not affect the substance of the argument.)

2 '"You must try for best outcome" is not a rule? What is it then?'

For every x, if Gx, then Mx : For every action, if that action produces the best outcome and is one you can possibly do, then you must try to do that action and hence try for the best outcome.

I'd call that an ethical rule.

3 I have fixed on the type of rule most relevant to your question but it's possible to have a universal rule when, for instance, there are plural and rivalrous values :

For every x, if Gx, then presumptively Mx. The presumption can be defeated if in a particular situation for action Gx grounds, for contextual reasons, a different moral property from M. That is to say, if a different moral property has priority in that specific situation. ('Whenever you make a promise then you should keep it' : in the real complexity of life a presumption is implicit. If the promise is to return a book, but returning the book would prevent you from saving an innocent life, then the presumption that you should keep your promise is defeated by the morally more significant consideration of saving an innocent life. The - to my mind - omnipresence of defeasible presumptions makes ethical rules merely rules of thumb, extremely rough guides, in moral deliberation and action. But that's another story.)

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