I haven't written this yet. You might possibly be interested in an essay on utilitarianism, but it doesn't say anything very original. Or in a note on Lucas's abuse of Gödel's theorem (he thought it proved that people can't be modelled as machines), which also says nothing that hasn't been said before. Or even in a short essay on Derek Parfit's so-called "Repugnant Conclusion", found e.g. in his "Reasons and persons".