"Morality does not require us to do the impossible" has long been an axiom in ethics, but the definition of "impossible" seems to be vague when we examine some extreme cases.

For example, silly mistakes are inevitable for almost everyone. And this implies that making silly mistakes, including those with devastating outcomes, cannot be immoral.

Another example involves racism. If someone has grown up in a racist environment like Nazi Germany, he is very likely to be racist. However, does this imply his attitude towards minorities is morally permitted?

It seems that we cannot simply draw a line between "possible" and "impossible". Can anybody suggest a plausible way out?

  • Google has no results for "Morality does not require impossibles", so I find it hard to believe that it's a central axiom in normative ethics. It's also barely grammatical. Can you give an actual quote from some normative ethicists who might phrase it differently? – curiousdannii Aug 21 '19 at 13:32
  • Moral impossibility is normally a RELATIVE concept not a pure normative concept. I do know many authors will define moral impossibility differently but the idea generally expresses there is a difficulty in doing the moral act for the person in question. Perhaps he is not phyically capable of doing the proper behavior at the right time & place it is needed. Another point is that the solution may not be a universal: that is, different solutions to the same moral problem at different times or places. Thus we get a subjective morality most of the time & a small percentage of universal solutions. – Logikal Aug 21 '19 at 13:35
  • @curiousdannii I am a beginner in ethics so I apologize for any incorrect use of terms. I got the idea from Shafer-Landau's The Fundamentals of Ethics, p 95, in a chapter on psychological egoism and its threat to morality. The author states that "we are not required to do the impossible - morality might be pretty demanding at times, but it can't be that demanding". – AkiraCA Aug 21 '19 at 13:46
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    @curiousdannii Ought implies can is Kant's formula. It is not entirely uncontroversial, but then nothing in ethics is :) I guess, the question is what types of impossibility then are morally relevant. Physical impossibility gives a free pass, presumably, softer "impossibilities" do not. – Conifold Aug 21 '19 at 20:06
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    @christo183 That is better, but still does not work. Mutually exclusive cans can both be "good". I guess, perfectionism takes the sentiment as far as it can coherently go. – Conifold Aug 22 '19 at 11:52

Your question reminds me of Sartre

Given the fundamental division of the human situation into facticity and transcendence, bad faith or inauthenticity can assume two principal forms: one that denies the freedom or transcendence component (“I can't do anything about it”) and the other that ignores the factical dimension of every situation (“I can do anything by just wishing it”). The former is the more prevalent form of self deception but the latter is common to people who lack a sense of the real in their lives.

So it seems to be a question about freedom, rather than ethics per se. Someone who is raised by Nazis is as free to embrace another, less racist, ideology as anyone (Sartre actually says there are no authentically free Nazis).

On the flip side, if we were not able to make mistakes in our potentially moral behaviour then anything would be done just by willing it, and we would not be free and condemned to be free.

So one way to answer the question about what is morally impossible is just to ask what we are free to do.


The basic idea is expressed in the dictum that 'ought implies can'. It cannot be the case that I ought to do X when this is a requirement of action, if I cannot do X. 'You ought to do action X (now) and this is a moral obligation you must fulfil (now)' presupposes that I can do it. If it is impossible for me to do X, how can the impossible be required of me as a moral obligation?

This looks straightforwardly the case - in the language of 'necessary conditions' the possibility of doing something is a necessary condition for having a moral obligation to do it.

Three points, however:

  1. It might be that while I cannot do X now - X is impossible for me now - I still have a moral obligation to do X at some future date when the impossibility has been removed. I cannot help a neighbour now, it might be, because I am in hospital with a broken leg but when I am up and about again, the moral obligation can come back into play.

  2. The notion of impossibility can take further analysis. Is it physical impossibility we are talking of - the impossibility, say, of doing X when X is inconsistent with the laws of nature ? Or merely the commonsense impossibility of the hospital case ?

  3. We should note a different kind of impossibility, one with an epistemological basis. Suppose I am unaware of someone's needs, someone I would recognise a moral obligation to help if I knew their needs. It cannot be the case that I have a moral obligation to help that person if I am ignorant of their predicament and cannot know of it in my present condition. This suggests another way of reading the dictum: I do not have a moral obligation to help X if I cannot know of the morally relevant situation they are in


If moral obligations are something humans come up with using rational means, then it makes sense to assume that one should not expect someone to do what is impossible. In this context a moral obligation is analogous to a legal requirement to behave correctly such as when crossing a street with a traffic light. There is no point in legislating behavior that is impossible to perform and there may be circumstances (such as silly decisions) that might excuse one for not behaving correctly if facing a judge and jury.

In that context humans make these moral obligations and humans fulfill them.

However, if one accepts a divine command theory, then humans do not make nor are they alone in fulfilling the moral obligations. All that is required is their obedience. Here is Michael W. Austin's description of it:

Roughly, Divine Command Theory is the view that morality is somehow dependent upon God, and that moral obligation consists in obedience to God’s commands. Divine Command Theory includes the claim that morality is ultimately based on the commands or character of God, and that the morally right action is the one that God commands or requires. The specific content of these divine commands varies according to the particular religion and the particular views of the individual divine command theorist, but all versions of the theory hold in common the claim that morality and moral obligations ultimately depend on God.

In this context something apparently impossible may be commanded, such as crossing the Red Sea or treating an enemy with justice and mercy. One can expect God, who gives the commands, will assist one in whatever is required, impossible or not. If a person makes a silly mistake and disobeys there may be ways to obtain forgiveness depending on the particular religion the disobedient person belongs to.

Austin, M. W. Divine Command Theory. Retrieved on August 21, 2019 from the Internet Encyclopedia of Philosophy at https://www.iep.utm.edu/divine-c/

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