What should we learn from past AI forecasts?

To inform the Open Philanthropy Project's investigation of potential risks from advanced artificial intelligence, and in particular to improve our thinking about AI timelines, I (Luke Muehlhauser) conducted a short study of what we should learn from past AI forecasts and seasons of optimism and pessimism in the field. In addition to the issues discussed on our AI timelines page, another input into forecasting AI timelines is the question, "How have people predicted AI -- especially HLMI (or something like it) -- in the past, and should we adjust our own views today to correct for patterns we can observe in earlier predictions?"1 We've encountered the view that AI has been prone to repeated over-hype in the past, and that we should therefore expect that today's projections are likely to be over-optimistic. To investigate the nature of past AI predictions and cycles of optimism and pessimism in the history of the field, I read or skim-read several histories of AI2 and tracked down the original sources for many published AI predictions so I could read them in context. I also considered how I might have responded to hype or pessimism/criticism about AI at various times in its history, if I had been around at the time and had been trying to make my own predictions about the future of AI. I can't easily summarize all the evidence I encountered that left me with these impressions, but I have tried to collect many of the important quotes and other data below. Then, in a final subsection, I summarize some questions I might have investigated if I had more time. I would be curious to learn whether people who read a set of sources similar to the set I consulted come away from that exercise with roughly the same impressions impressions I have. I would also be curious to hear how many AI scientists who were active during most of the history of the field share my impressions. The histories I read left me with the impression that some (but not all) of the earliest AI researchers -- starting around the time of the Dartmouth Conference in 1956 -- thought HLMI (or something like it) might only require a couple decades of work. For example, Moravec (1988) claims that John McCarthy founded the Stanford AI project in 1963 "with the then-plausible goal of building a fully intelligent machine in a decade" (p.