Online research in philosophy

Objective consequentialism is often criticized because it is impossible to know which of our actions will have the best consequences. Why exactly does this undermine objective consequentialism? I offer a new link between the claim that our knowledge of the future is limited and the rejection of objective consequentialism: that ‘ought’ implies ‘can’ and we cannot produce the best consequences available to us. I support this apparently paradoxical contention by way of an analogy. I cannot beat Karpov at chess in spite of the fact that I can make each of many series of moves, at least one of which would beat him. I then respond to a series of objections. In the process I develop an account of the ‘can’ of ability. I conclude with some remarks about the bearing this attack has on subjective consequentialism.

Frances Howard-Snyder has argued that objective consequentialism violates the principle that ‘ought’ implies ‘can’. In most situations, she claims, we cannot produce the best consequences available, although objective consequentialism says that we ought to do so. Here I try to show that Howard-Snyder's argument is unsound. The claim that we typically cannot produce the best consequences available is doubtful. And even if there is a sense of ‘producing the best consequences’ in which we cannot do so, objective consequentialism does not entail that we ought, in this sense, to produce the best consequences.

“Perhaps the most common objection to consequentialism is this: it is impossible to know the future…This means that you will never be absolutely certain as to what all the consequences of your act will be…there may be long term bad effects from your act, side effects that were unforeseen and indeed unforeseeable…So how can we tell which act will lead to the best results overall – counting all the results? This seems to mean that consequentialism will be unusable as a moral guide to action. All the evidence available at the time of acting may have pointed to the conclusion that a given act was the right act to perform – and yet it may still turn out that what you did had horrible results, and so in fact was morally wrong. Indeed, if will never be possible to say for sure that any given act was right or wrong, since any event can continue to have further unseen effects down through history. Yet if it is impossible to tell whether any act is morally right or wrong, how can consequentialism possibly be a correct moral theory?”.

Frances Howard-Snyder argues that objective consequentialism should be rejected because it violates the principle of ‘ought’ implies ‘can’ in asking us to do what we cannot. In this comment I suggest that Howard-Snyder does not take sufficiently seriously the chief defence of objective consequentialism, which reformulates it so that it applies only to actions we can perform. Nonetheless, I argue that there are arguments relating to ‘ought’ implies ‘can’ which discredit objective consequentialism even if it is thus reformulated. These arguments also cause problems for a reformulated version of subjective consequentialism.

This paper examines the relationship between Savage's sure thing principle and the value of information. We present two classes of results. First, we show that, under a consequentialist axiom, the sure-thing principle is neither sufficient nor necessary for perfect information to be always desirable: specifically, under consequentialism, the sure thing principle is not implied by the condition that perfect information is always valuable; moreover, the joint imposition of the sure thing principle, consequentialism and either one of two state independence axioms does not imply that perfect information is always desirable. Second, we demonstrate that, under consequentialism, the sure thing principle is necessary for a nonnegative value of possibly imperfect information (though of course the principle is still not sufficient). One implication of these results is that the sure thing principle, under consequentialism, plays a somewhat different role in ensuring dynamic consistency in decision making under uncertainty than does the independence axiom in decision making under risk.

In a recent article, Adam Elga outlines a strategy for “Defeating Dr Evil with Self-Locating Belief”. The strategy relies on an indifference principle that is not up to the task. In general, there are two things to dislike about indifference principles: adopting one normally means confusing risk for uncertainty, and they tend to lead to incoherent views in some ‘paradoxical’ situations. I argue that both kinds of objection can be levelled against Elga’s indifference principle. There are also some difficulties with the concept of evidence that Elga uses, and these create further difficulties for the principle.

The idea of a probabilistic logic of inductive inference based on some form of the principle of indifference has always retained a powerful appeal. However, up to now all modifications of the principle failed. In this paper, a new formulation of such a principle is provided that avoids generating paradoxes and inconsistencies. Because of these results, the thesis that probabilities cannot be logical quantities, determined in an objective way through some form of the principle of indifference, is no longer supportable. Later, the paper investigates some implications of the new principle of indifference. To conclude, a re-examination of the foundations of the so-called objective Bayesian inference is called for.

The idea of a probabilistic logic of inductive inference based on some form of the principle of indifference has always retained a powerful appeal. However, up to now all modifications of the principle failed. In this paper, a new formulation of such a principle is provided that avoids generating paradoxes and inconsistencies. Because of these results, the thesis that probabilities cannot be logical quantities, determined in an objective way through some form of the principle of indifference, is no longer supportable. Later, the paper investigates some implications of the new principle of indifference. To conclude, a re-examination of the foundations of the so-called objective Bayesian inference is called for.

Instrumental rationality requires that an agent selects those actions that give her the best outcomes. This is the principle of consequentialism. It may be that it is not the only requirement of this form of rationality. Considerations other than the outcomes may enter the picture as well. However, the outcome(s) of an action always play a role in determining its rationality. Seen in this light consequentialism is a minimum requirement of instrumental rationality. Therefore, any theory that tries to spell out the implications of instrumental rationality, in particular expected utility theory, should subscribe to the principle of consequentialism. Or so it seems.