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Moral Indeterminacy
By S. Matthew Liao

Crowdsourcing: I’m teaching a graduate seminar on Moral Indeterminacy in the Fall. I’d be interested in learning about ‘must reads’ and ‘must cover’ topics. Here is a draft description of the course:

It seems impermissible to kill one innocent person to save five other innocent people from being killed. At the same time, many people have the intuition that it may be permissible to kill one innocent person to save, e.g., one million people. Suppose that there is something to these intuitions. Is there a precise threshold when the act of killing an innocent person changes from impermissibility to permissibility, or is the boundary fuzzy? Is the source of this indeterminacy due to semantic vagueness in the term ‘permissibility’ or lack of adequate knowledge about what counts as permissible? Or does the indeterminacy stem from vagueness in the world? What is the difference between vagueness and indeterminacy? How should we go about deciding what to do when faced with a case of moral indeterminacy? In this seminar, we shall, among other things, critically review some of the most popular philosophical approaches to vagueness including semantic, epistemological, and ontological approaches; consider whether the source of moral indeterminacy may be different from non-moral indeterminacy; and apply these insights to normative issues such as the defensibility of threshold deontology and the problem of incommensurability in population ethics.

Many thanks in advance!


  1. 1. Posted by Mike Almeida | April 25, 2013 2:18 pm

    There is Stephen P. Schwartz (1999). Why It Is Impossible to Be Moral. American Philosophical Quarterly 36 (4):351 – 360. But lots of interesting papers collected in PhilPapers, Vagueness in Ethics and Law,

  2. 2. Posted by S. Matthew Liao | April 26, 2013 7:31 pm

    Thanks, Mike!

  3. 3. Posted by Christian Lee | April 27, 2013 3:43 am

    I wrote a chapter on this issue in a dissertation. It’s a super interesting topic. I’d suggest getting into the recent literature on incommensurability: e.g. Broome, Wasserman, Klocksiem, Chang, etc. Philosophers seem to think that purported cases of incommensurability are just cases of vagueness in value. I think they’re right. But there’s different ways to characterize the vagueness at issue. As for vagueness, I’d recommend Barnett.

    Barnett, David 2009. Is Vagueness Sui Generis? Australasian Journal of Philosophy 87/1: 5-34.

    Barnett, David 2011. Does Vagueness Exclude Knowledge? Philosophy and Phenomenological Research 83/1: 22-45.

  4. 4. Posted by S. Matthew Liao | April 28, 2013 6:38 pm

    Thanks for these helpful suggestions, Christian! I’d be pleased to learn more about your work too.

  5. 5. Posted by Dan Dennis | April 30, 2013 12:38 am

    Hi Matthew

    This guy has a couple of papers on ‘What to do when you don’t know what to do’:

  6. 6. Posted by S. Matthew Liao | April 30, 2013 5:16 am

    Thanks, Dan!

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