welcome to the nonlinear library, where we use text-to-speech software to convert the best writing from the rationalist and ea communities into audio. This is: Longtermism', published William_MacAskill on the effective altruism forum. This post discusses the introduction and definition of the term ‘longtermism’. Thanks to Toby Ord, Matthew van der Merwe and Hilary Greaves for discussion. [Edit, Nov 2021: After many discussions, I've settled on the following informal definition: Longtermism is the view that positively influencing the longterm future is a key moral priority of our time. This is what I'm going with for What We Owe The Future. With this in hand, I call strong longtermism is the view that positively influencing the longterm future is the key moral priority of our time. It turns out to be suprisingly difficult to define this precisely, but Hilary and I give it our best shot in our paper.] Up until recently, there was no name for the cluster of views that involved concern about ensuring the long-run future goes as well as possible. The most common language to refer to this cluster of views was just to say something like ‘people interested in x-risk reduction’. There are a few reasons why this terminology isn’t ideal: It’s cumbersome and somewhat jargony It’s a double negative; whereas focusing on the positive (‘ensuring the long-run future goes well’) is more inspiring and captures more accurately what we ultimately care about People tend to understand ‘existential risk’ as referring only to extinction risk, which is a strictly narrower concept You could care a lot about reducing existential risk even though you don’t care particularly about the long term if, for example, you think that extinction risk is high this century and there’s a lot we can do to reduce it, such that it’s a very effective thing even by the lights of the present generation’s interests. Similarly, you can care a lot about the long-run future without focusing on existential risk reduction, because existential risk is just about drastic reductions in the value of the future. (‘Existential risk’ is defined as a risk where an adverse outcome would either annihilate Earth-originating intelligent life or permanently and drastically curtail its potential.) But, conceptually at least (and I think in practice, too) smaller improvements in the expected value of the long-run future could be among the things we want to focus on, such as changing people’s values, or changing political institutions (like the design of a world government) before some lock-in event occurs. You might also think (as Tyler Cowen does) that speeding up economic and technological progress is one of the best ways of improving the long-run future. For these reasons, and with Toby Ord’s in-progress book on existential risk providing urgency, Toby and Joe Carlsmith started leading discussions about whether there were better terms to use. In October 2017, I proposed the term ‘longtermism’, with the following definition: “Longtermism =df the view that the most important determinant of the value of our actions today is how those actions affect the very long-run future.” Since then, the term ‘longtermism’ seems to have taken off organically. I think it’s here to stay. Unlike ‘existential risk reduction’, the idea behind ‘longtermism’ is that it is compatible with any empirical view about the best way of improving the long-run future and, I hope, helps immediately convey the sentiment behind the philosophical position, in the same way that ‘environmentalism’ or ‘liberalism’ or ‘cosmopolitanism’ does. But getting a good definition of the term is important. As Ben Kuhn notes, the term could currently be understood to refer to a mishmash of different views. I think that’s not good, and we should try to develop some standardisation before the term is locked in to something suboptimal. I think that there are three natural concepts in this area, which we should distinguish. My proposal is that ...