There is another way to use considerations of symmetry against the harm thesis: we want to die later, or not at all, because it is a way of extending life, but this attitude is irrational, Lucretius might say, since we do not want to be born earlier (we do not want to have always existed), which is also a way to extend life. As this argument suggests, we are more concerned about the indefinite continuation of our lives than about their indefinite extension. (Be careful when you rub the magic lamp: if you wish that your life be extended, the genie might make you older!) A life can be extended b...