I have recently written a series of articles about problems in utilitarian ethics that are highly relevant for effective altruism.
A first article describes why I became a utilitarian and what kind of utilitarianism I endorse (i.e. preference, rule, variable critical level, variance normalized,…).
The second article deals with the problems of population ethics and argues for a variable critical level utilitarianism, a kind of critical level utilitarianism where everyone is free to choose his or her own critical level in each different situation. Total, average, critical level, negative and person affecting utilitarianisms are all different special cases of variable critical level utilitarianism. With variable critical level utilitarianism, we can avoid counter-intuitive problems in population ethics. This issue becomes crucial when we have to choose between avoiding actual suffering (e.g. of factory farmed animals today) versus increasing well-being in the long-term future (e.g. avoiding existential risks).
The next two articles deal with the problem of interpersonal comparison of well-being. The first discusses a general method of utility normalization, based on an analogy between measuring utilities and measuring temperatures. This applies to utility functions that have continuous inputs (perceptions or experiences). When inputs are discrete another method is possible that counts the amount of just-noticeable differences in utility. The utility function now looks like a multidimensional staircase where the steps can have different widths. With this method we can compare the utilities of for example insects with humans.
Finally, I deal with the more exotic problem of counting persons and conscious experiences. This problem becomes important when we deal with future conscious artificial intelligence and whole brain emulations, but it is also relevant when we discuss insect sentience or split-brain patients.