Yes, you do have a moral responsibility toward the apparent perpetrator. This responsibility results from two factors. First, what appears to you to be a criminal act in progress may not be one: perhaps these guys a filming a movie, practicing for a play, or just horsing around. Secondly, your response should be proportional to the threat to the crime victim as modified, perhaps, by the culpability of the offender. When you surprise a large man who is vigorously assaulting another with a knife, you have strong reason to believe that the danger to the victim is imminent and substantial; so a forceful response seems appropriate to reduce this danger, even if it risks harm to the assailant. On the other hand, when you surprise a teenager snatching a $10 bill from a shopper and turning for a quick get-away, you should not risk serious physical harm to the thief when the only danger you thereby reduce is the danger that the shopper will lose the $10. You should be especially reluctant to risk harm to the...

Yes, we ought to follow rules of logic, rules of scientific method, rules of rational choice, and rules of prudence, for example. Sure, we are often not doing anything unethical by violating such rules, so we may not have a moral reason to obey. But not all good reasons are moral reasons. And we typically have good non-moral reasons to follow rules like the ones mentioned above.

Your puzzlement seems to arise from the symmetry of the situation. One of you will die, each prefers his/her own survival to that of the other, and so on. Looking at it from an impartial standpoint, you see no good reason why either one of you should be preferred. But there is a good reason: the other one -- not you -- is the cause of the problem, the cause of the need for one of you to die. You have a plausible reason for using force against the other, a reason that she lacks. While you cannot survive without using force against her, she can survive (could have survived) without using force against you. To be sure, there are exceptional cases where the other must attack you to survive. She may be coerced by a third party aiming a gun at her, for example, or she may be unable to keep herself afloat without the only available life preserver which you are wearing and need just as urgently. And there are other exceptional cases where the other firmly believes -- falsely but on good grounds -- that...

This is an interesting and difficult question. One might start with the presumption that a company's hiring may be conducted in whatever way its top officers deem most advantageous. Thus imagine a company that has two positions to fill and is considering four candidates. The hiring officers rank these candidates in the following order: Alice, Ben, Celia, David. So they would like to hire Alice and Ben. But unfortunately Alice is married to David, and she will decline unless David is also made an offer. So the hiring officers discuss whether the firm is better off with Alice and David or with Ben and Celia. They determine that the Alice-David combination is more advantageous, and so they promise Alice that, if she accepts, David will also be hired. Does Ben have a complaint in this case? I don't think so. It is true that, other things equal, he would add more value to the firm than David would. But other things are not equal: if Ben is hired over David, then Alice will decline; whereas if David is...

Part of what makes it wrong to hit or torture people is surely that such behavior causes pain. It follows naturally that, when such conduct is wrong, it is more wrong when it inflicts more pain. An unprovoked slap on your thigh by a stranger is a lesser wrong than a full strength blow to your nose. By the same logic, it would seem to be less wrong to hit a stranger if you ensure (perhaps by first inviting him to a good glass of Scotch or through prior local anaesthesia) that he feels little or no pain. And it would then also seem less wrong if you hit his "bad" leg (where he has lost feeling after a botched appendicitis) rather than his "good" leg (which has normal pain sensitivity). This is easily extended to saying that it is less wrong to hit one stranger's "bad" leg than another stranger's "good" leg. And this in turn pretty much is the proposition you query: other things equal, a behavior is less wrong if it causes less pain. Of course, it does not follow that a behavior is not wrong if it...

Such behavior would seem to manifest an error of reasoning only if the person also has a commitment never to act unethically and somehow believes that she is acting in accordance with this commitment. Most people have no such commitment. They are ready to act unethically in certain situations and, when they do, there is nothing wrong with their reasoning. I don't think that people thus acting unethically are always emotionally indifferent to unethical behavior. They may emotionally enjoy the thrill of doing something unethical. Or they may be disturbed by their conduct, albeit not disturbed enough to avoid it. For example, someone finds her neighbor's wallet with $4000 in it. She is emotionally upset by the idea of stealing the money, and she would refrain if the amount were much smaller. But with such a large amount she decides to accept some emotional distress for the sake pocketing the cash. No emotional indifference here, and also no error of reasoning.

It's credible that morally correct behavior is less common among very young children and the mentally impaired than among the rest. But your point about prisons does not seem to me to lend sufficient support to the larger positive correlation you suggest for at least three reasons. First, a great deal of selfish, immoral and highly damaging behavior -- e.g. in politics or in the business world -- is actually not criminal; and more intelligent people are probably substantially overrepresented among those engaging in such behaviors. Second, many people commit crimes but nonetheless manage to avoid prison -- either by not getting caught or by creating enough reasonable doubt to sway a prosecutor or a jury; and in this group, too, the more intelligent are likely to be overrepresented. Third, a surprisingly high percentage of prison inmates (esp. in the US) are actually innocent of the crime they have been convicted for, and they languish in jail even though they have not acted immorally or have...

There is surely some such change. For example, it was not wrong 2000 years ago to have as many children as you could comfortably raise with your spouse or partner; but today -- when global warming and resource scarcity are real threats and when it is quite possible for affluent people to adopt children who would otherwise grow up under very oppressive conditions -- it would be wrong to have a dozen children. But the change here may well be explainable in terms of some unchanged ethical principle that persists. For example, Kant's principle that tells us to permit ourselves only such conduct as we could permit to all others as well. In 12 AD, it would have been fine if everyone had felt free to have as many children as s/he could afford to raise. Today such conduct would impose great harms of future generations as well as on various impoverished contemporaries. Some dramatic changes in the prevailing morality do not have such an explanation. Suppose, for example, that social and technological...

You suggest that Kant's criterion of wrong conduct turns on this question: "If everyone acted the way I am proposing to act, would this have undesirable consequences?" I think Kant's actual question differs in two respects. Kant is not asking whether the agent would like some fictional world (find it desirable), but whether the agent can will it and her own proposed conduct in it. And the world Kant envisioned is not one in which all act the way the agent is proposing to act, but one in which all are permitted (and take themselves to be permitted) so to act. So Kant's question is: "Can I will the action I am considering along with its universal permission?" The basic idea here is that I should not permit myself an action that I cannot permit all others at the same time. Let's see how this plays out in Kant's promising example. The agent considers extricating himself from financial difficulty by making a false (lying) promise. He then asks himself whether, in a world in which all took themselves to...

Letting terminally ill people die will do little to slow population growth because the vast majority of these people are not going to have (additional) children anyway. But there are other solutions that would actually work. You write that there seems to be no slowing of procreation. This is quite false. Total fertility rates (average number of children per woman) have fallen spectacularly since 1955 ... but only in countries and regions where poverty has been meaningfully reduced. For example, the TFR of East Asia fell from 5.42 to 1.72 (below the rate of reproduction) -- and East Asia is the most populous region on Earth. So this is highly significant. There were large drops also in Portugal, Australia, Botswana, Italy, and so on. Where poverty persists, on the other hand, so do high TFRs. Many African states are good examples of this. Niger's TFR has increased from 6.86 to 7.15, and other high-poverty countries (Mali, Senegal, Equatorial Guinea) are not far behind. The evidence is overwhelming,...