Wednesday, July 18, 2012

The Ought Implies Can Principle

A friend and I were talking about the recent blog post and the "ought implies can" principle. We agreed that we should make the principle explicit in a somewhat philosophical form, so here goes:

S is morally obligated to do X at t if and only if S is commanded to do X at t and it is within S's causal power to do X at t in the actual world.

This formulation prevents against the idea that whatever one can do, one ought to do (hence the "command" clause). It also helps avoid problems that arise when it is possible for S to perform X at t in one sense, but not in another. For instance, if S is commanded to fly (without any aids) it is logically (and even metaphysically) possible for S to fly; yet, if S is a human, S cannot perform this act. In fact, it is physically impossible for S to fly, so that it is not within S's causal power to fly at time t. So, if someone could possibly perform some morally-commanded action in the actual world, then they have an obligation to do such. If, however (per impossible, as I happen to think), S is morally-commanded to do some action at a time that lies outside of her causal power in the actual world at that time, then S would not be morally obligated to do such a thing at that time.

H/T to Pranav Bethala. Although, I wouldn't tip my hat even if I had one, so perhaps we can change it to "hat throw"?
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  1. How would this principle here relate to, say, the Mosaic Law? The Israelites ought to have followed the law, but they didn't. But could they? The Bible seems to teach that we can't fully follow the law, but the Israelites still ought to have followed it were blameworthy for not following it.

  2. Just recently started reading your blog, and I am just curious where you stand theologically speaking. Do you subscribe more to the neo-theism of William Lane Craig or more to the classical theism of Edward Feser, for example? Thanks! :)

  3. Hi Kyle, that's a very interesting question! I take the biblical possibility of keeping the law in its entirety to be a colloquial, or functional usage of possibility. That is to say it is logically possible we refrain from each and every act of sin (also commensurate with those to whom the Mosaic law applied), and it is within one's causal power to fulfill each part. However, it's not really feasible. A weak analogy may be if we consider the case of my walking across America, from one coast to the next, in some relatively reasonable period of time (say, 4 weeks, I don't know). It's completely within my causal power to bring it about that I complete such a journey in the required time, but seeing as I am out of shape, it's really not colloquially possible. I also use the word "feasible" for this kind of stuff. Does that help at all?

  4. Hi Moi, thanks for commenting and especially reading! Welcome to the blog. :)

    I'd say I fall more towards Craig than Feser, though I certainly appreciate everything Ed has done and quote his blog often (especially on my FB page lol).

  5. Just to be clear, I would not self-identify (and neither would WLC, as far as I can tell) as a "neo-theist." Whatever is meant by that term here, it is commonly used on the popular level to be a larger set encompassing things like process theology and open theism, neither of which I support. :)


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