principle that, in deciding what is good and what is bad for a given individual, the ultimate criterion can only be his own wants and his own preferences." Harsanyi adds two caveats. Firstly, people sometimes have irrational preferences. To deal with this, Harsanyi distinguishes between "manifest" preferences and "true" preferences. The former are those "manifested by his observed behaviour, including preferences possibly based on erroneous factual beliefs, or on careless logical analysis, or on strong emotions that at the moment greatly hinder rational choice"; whereas the latter are "the preferences he would have if he had all the relevant factual information, always reasoned with the greatest possible care, and were in a state of mind most conducive to rational choice." It is the latter that preference utilitarianism tries to satisfy. The second caveat is that antisocial preferences, such as sadism, envy, and resentment, have to be excluded. Harsanyi achieves this by claiming that such preferences partially exclude those people from the moral community: Negative utilitarianism In The Open Society and its Enemies (1945), Karl Popper argues that the principle "maximize pleasure" should be replaced by "minimize pain". He believes that "it is not only impossible but very dangerous to attempt to maximize the pleasure or the happiness of the people, since such an attempt must lead to totalitarianism." He claims that: The actual term negative utilitarianism itself was introduced by R. N. Smart as the title to his 1958 reply to Popper in which he argues that the principle would entail seeking the quickest and least painful method of killing the entirety of humanity. In response to Smart's argument, Simon Knutsson (2019) has argued that classical utilitarianism and similar consequentialist views are roughly equally likely to entail killing the entirety of humanity, as they would seem to imply that one should kill existing beings and replace them with happier beings if possible. Consequently, Knutsson argues: Furthermore, Knutsson notes that one could argue that other forms of consequentialism, such as classical utilitarianism, in some cases have less plausible implications than negative utilitarianism, such as in scenarios where classical utilitarianism implies it would be right to kill everyone and replace them in a manner that creates more suffering, but also more well-being such that the sum, on the classical utilitarian calculus, is net positive. Negative utilitarianism, in contrast, would not allow such killing. Some versions of negative utilitarianism include: Negative total utilitarianism: