Perhaps I can play the devil's advocate and rebuild the case for thinking that systematic ethical theory gets us nowhere. There are actually many different systematic theories--utilitarian, contractarian, deontological, etc.--but the trouble is they clash. The defenders of such theories often agree on particular moral judgments, but as to the abstract principles that define these systems, the experts disagree. In fact, it is precisely disagreement over the principles of these systems that animates much current academic debate in ethics. Yet if not even the experts can agree on which of their systematic principles are correct and which incorrect, why should anyone else rely on them? The theories in question are just as disputable as any real moral decision they could be invoked to justify. Again, systematic ethical theories are often defended on the grounds that they are like systematic theories in empirical science. (Rawls, for example, makes this move.) Yet empirical theories in science are reliable...

Some folks are enamored of the idea of “shooting dead an intruder in one’s house without asking questions,” but I’m not one of them. Necessary self-defense has always been a basic part of common law, but it is quite another thing to kill a man or woman on the sole pretext that that person is an intruder, whether or not the person constitutes a genuine threat to anybody in particular. Even jurisdictions that have stand-your-ground laws, or “castle” laws, generally require that you have a genuine fear of harm, or at least a genuine fear of a serious felony, before you are justified in using deadly force. And even then, the level of force must be necessary. Stephen Maitzen is entirely right when he points out that an undocumented alien is almost certainly not a genuine and immediate threat to you. Beyond this point, however, the notion that you can lawfully kill someone just because that person has intruded into your home now circulates broadly, and it is, in fact, legally false. You have no such legal...

Allen Stairs is right in suggesting that it is possible to lie by saying nothing, and perhaps it is worth adding that lies of this sort often form the basis of prosecutions for fraud. Fraud is legally complicated, but the basic idea is that you can injure someone by causing that person to rely on your assurances, even when you know that your assurances are false. Many legal systems assume that such conduct should sometimes be punished, depending on the circumstances, but they also assume that false assurances (or false representations) can come from what you don't say as much as from what you do say. For example, if I sell you a car without telling you that it has no brakes, and I omit this fact knowingly, my conduct might well be punishable as fraud. One can label such conduct with a variety of names, of course, but the basic idea is that there is something fundamentally wrong and dishonest about it, and many societies have sought to punish it. A key element in these situations is trust. If I sell...