Abstract: What scientific experiments, if any, are we justified in performing on animals in order to answer philosophical questions such as the distribution of complex feelings across species? Would researchers, for example, be justified in inducing behavioral signs of depression in monkeys if they thought the results could help to resolve the metaphysical question, whether nonhumans have the capacity to feel, for example, the social anxiety that results from thinking that others think you are worthless? To make progress on this issue, I proceed in three steps. First, I review the case for thinking that cynomulgus monkeys experience social-stress induced depression, a higher order mental state some humans find worse than death. Second, I introduce and rebut three objections to the idea that we can legitimately attribute this feeling to monkeys. Third, I conclude by outlining an invasive experiment that might help to settle the Distribution Question and I ask whether it would be humane to carry it out.
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