DARPA Program managers have a tenure of four to five years. Similarly, before 2001, directors did not stick around much longer. Obviously institutional memory lasts longer than any individual but memory of specific programs dies out quickly because DARPA is relatively tiny and flat so there is only one PM running any program and people pay much more attention to their own work than other people’s. This transient memory about failed programs means less friction around creating a program that ‘has been tried before’ and makes it more likely that DARPA can explore Unexploited Leonardo Ideas.
A former program manager described how there have been multiple instances of program managers starting successful programs that they discovered later were almost the same as failed programs from the past. If there were enough people around who had seen the failure, the program manager would have had to not just argue for the validity of their program on its own grounds, but address the shadow cast by the failed program. Of course It’s rational to try something that failed in the past as long as you explicitly call out why you will succeed when they failed but Small amounts of friction can have large effects. Essentially, the transient memory about specific ideas allows them to be judged on their own merits instead of dealing with baggage from the past.
It’s entirely possible that short institutional memory about specific programs could lead to people trying terrible ideas over and over again. You see that with certain forms of government, for example. If there are high epistemological standards (enforced by Every program at DARPA is intensely technically scrutinized by the tech council and DARPA PMs use seedling programs to ‘acid test’ the riskiest pieces of a program idea) and there are no externalities to the failure, trying things over and over again has capped downside. Additionally, the institutional memory is short, but not that short - you will only get a complete turnover once every five years or so, which is enough time for the constraints in the world to change.
In a way, short institutional memory about programs is like the temporal version of how Federated systems make it so disruptive changes cannot be completely damped out.