the desired trade-off between present and future welfare. "Pure time preference" debates The pragmatic factor usually results in a "pure time preference" factor in the social discount rate, that a pleasurable experience at a certain date is intrinsically more valuable than the exact same experience at a later date, and that the life of a person born sooner has more intrinsic value than the life of a person born later. According to philosopher Toby Ord, while this is common practice in the economics community, most philosophers consider a "pure time preference" to lack intrinsic moral justification. Frank Ramsey, himself, labeled it "ethically indefensible". Ord also argues that, given the long and unfortunate human history of discounting the welfare of outgroups, the burden should be on those proposing a pure time preference to establish its necessity. Intuitively, it seems odd that the welfare of an 80-year-old born in 1970 is intrinsically superior to the welfare of an 80-year-old born in 1980; in the context of social (rather than private) discount rates, when asked for their preferences over the welfare of others, most peoples' apparent "pure time preferences" becomes smaller or even disappears. Philosopher Derek Parfit states "No one suggests that... we should adopt a Spatial Discount Rate. No one thinks that we would be morally justified if we cared less about the long-range effects of our acts, at some rate n percent per yard. The Temporal Discount Rate is, I believe, as little justified." In contrast, Andreas Mogensen argues that a positive rate of pure time preference can be justified on the basis of kinship. That is, common-sense morality allows us to be partial to those more closely related to us, so "we can permissibly weight the welfare of each succeeding generation less than that of the generation preceding it." When considering longer time periods, a fixed "pure time preference" discount rate becomes extremely counterintuitive; a 1% rate implies that Tutankhamun should ethically value a single day of his life over the sum total entire lives of everyone living today. Over long periods, peoples' stated preferences become extremely hyperbolic. Critics worry that valuing the individual welfare of future generations can, if taken to an extreme, lead to a problematic 'Pascal's mugging' conclusion that current welfare has relatively negligible value. In global climate change This topic has recently been very controversial and highly debated. Since there is such a strong probability that