Given the ambiguity of the evidence and the depth of the underlying issues, it is interesting that the developers of portfolio insurance do not take the easy option of denying that it had a significant role in the 1987 crash. Leland and Rubinstein are both broadly "orthodox" economists and efficient-market theorists (see, for example, Rubinstein 2001). How do they reconcile this with their acceptance that it "isn't ridiculous to say that portfolio insurance was a significant factor in the market crash" (Rubinstein interview)?

Donald MacKenzie, An Engine, Not a Camera, loc. 865