Are there different possible outcomes of the future? Or phrased more broadly: do ontological possibilities exist? One may think that much depends on our answer to this question. For instance, if ‘ought’ implies ‘can’, and the only real ‘can’ there is is whatever in fact happens, it might seem to follow that the only thing that could ‘ought to happen’ is what in fact happens.
Ontological possibilities here stand in contrast to what we may call hypothetical, or ex-ante possibilities. That is, we are clearly able to think in terms of different outcomes being possible, and to then plan and take action based on such thinking, but that does not imply that those outcomes were ever genuine possibilities in a deep ontological sense.
An Objection Against the Meaningfulness of Ethics
My main reason for raising this issue of ontological possibilities has to do with ethics – more specifically, it has to do with an objection that one might be tempted to level against the sensibility and meaningfulness of ethics. For in light of the ought-implies-can note above, one might claim that ontological possibilities are necessary in order for ethics proper to get off the ground, and indeed for engagement in ethical reasoning, decision-making, and action of any kind to even make sense. This is a combustible and controversial claim, to be sure, yet I shall entertain no discussion of it here. (I should note that I do not endorse the claim, as I believe that ex-ante possibilities are in any case sufficient for ethics to make sense.)
Instead, my goal here is to make a conditional argument. I will argue that if one thinks ontological possibilities are required for “the meaningfulness of ethics” – i.e. for engagement in ethical reasoning, decision-making, and action to make sense – then one cannot reasonably reject such “meaningfulness” with the claim that ontological possibilities do not exist. One reason why is that we do not know with certainty whether such possibilities are real or not, and, as far as I can tell, we all but surely never will.
Why We Cannot Dismiss Ontological Possibilities
In order to say whether ontological possibilities exist, one approach might be to look toward what is arguably our most fundamental and well-tested theory of the world, namely quantum mechanics, to see what, if anything, it might say about it.
The answer seems to depend on which interpretation of quantum mechanics is correct, a matter on which there is much disagreement among experts. In light of such disagreement, it seems reasonable to maintain a substantial degree of uncertainty regarding which interpretation, if any, is true. This in turn leaves us uncertain as to whether the world unfolds according to deterministic laws or not.
Out of the 14 (at the time of writing) established interpretations of quantum mechanics listed on this Wikipedia page, only four are deterministic, seven are indeterministic, while three are agnostic. Consequently, although the deterministic interpretations include the relatively popular Many Worlds Interpretation, it still seems overconfident to be completely certain that the right interpretation, to the extent there is one, is deterministic. Indeed, among the 14 interpretations mentioned above, one of them, the transactional interpretation, is – at least in some formulations – explicitly realist about ontological possibilities; a “Many Possibilities Interpretation”, if you will.
Combining these considerations, one could reasonably conclude that it is overconfident to maintain more than, say, a 99 percent credence in the claim that ontological possibilities do not exist. (Of course, one could argue for the same conclusion with reference to various other reasons than just those raised above, such as a general humility heuristic regarding the ontological nature of the world. Note also that the exact credence is not important; the point is just that there is a non-negligible probability that ontological possibilities exist.)
Implications for (the Objection Against) the Meaningfulness of Ethics
The conclusion above means that, if ontological possibilities are required for “the meaningfulness of ethics” – the conditional assumption that was our starting point – then the rejection of ethics based on the supposed non-existence of ontological possibilities is unwarranted.
To be sure, one could argue that if ontological possibilities are required for “the meaningfulness of ethics”, then it seems likely that such meaningfulness does not obtain. Yet that is a far cry from a refutation of such meaningfulness. By analogy, consider the claim that risks of very bad future outcomes are low. Even if this claim were true, it does not follow that such risks can reasonably be dismissed.
When the stakes are sufficiently high, it is not reasonable to dismiss low probabilities. And when we are discussing the meaningfulness of ethics, it seems that the stakes could not be greater, as what is at issue is whether there are any stakes at all. In light of such stakes, it seems that even extremely low probabilities should be taken seriously. Thus, if ontological possibilities are required for the meaningfulness of ethics, it seems that the epistemic possibility of the reality of such ontological possibilities should be taken seriously indeed.
Moreover, when considering the outcomes of the options before us, an emerging asymmetry appears to make the choice clear. For if ontological possibilities are real, and ethical action amounts to trying to realize the best of these possibilities – to create the best ontologically possible world, if you will, or at the very least to avoid the worst ones – it would seem that we have good reason to try to realize the better over the worse of these possibilities. If, on the other hand, ontological possibilities are not real, trying to create a better world appears to have no cost (in terms of which ontological possibilities end up getting realized). We thus seem to have a strong reason in favor of trying to create a better world, and no compelling reason against it.
Lastly, if we entertain the negation of the assumption that served as our starting point, and thus assume that ontological possibilities are not required for the meaningfulness of ethics – again without saying whether this claim is true or not – we appear to arrive at the same conclusion: we have no reason to consider ethics meaningless. In sum, no matter our starting point, the meaningfulness of ethics seems on firm ground.