No, that would be evidence for it. I know you are trying to show I am having it both ways, but I am not. Think of the full tree of possibilities: ultimatum/no-ultimatum, bluff/real, rational-refusal/irrational-refusal. If real ultimatum had been issued and Saddam had then refused for irrational reasons, that would be strong evidence against the plan, because that’s the situation which is predicted to go well. And that’s the situation Punoxysm thought he’d found, but he hadn’t.
(Actually, you’re the second person today to think I was doing something like that. I mentioned on IRC I had correctly predicted to Gawker in late 2013 that the black-market BMR would soon be busted by law enforcement—as most of its employees would be within two months or so while setting up the successor Utopia black-market—mentioning that among other warning signs, BMR had never mentioned detecting attempts by law enforcement to infiltrate it; someone quoted at me that surely ‘absence of evidence is evidence of absence’? Surely if BMR had claimed to be seeing law enforcement infiltration I would consider that evidence for infiltration, so how could I turn around and argue that lack of BMR claims was also evidence for infiltration? Yes, this is a good criticism—in a binary context.
But this was more complex than a binary observation: there were at least 3 possibilities. 1. it could be that law enforcement was not trying to infiltrate at all, 2. it could be they were trying & had failed, or 3. it could be that they were trying & succeeded. BMR’s silence was evidence they didn’t spot any attacks, so this is evidence that law enforcement was not trying, but it was also evidence for the other proposition that law enforcement was trying & succeeding; a priori, the former was massively improbable because BMR was old and notorious and it’s inconceivable LE was not actively trying to bust it, while the latter was quite probable & had just been done to Silk Road. Hence, observing BMR silence pushed the infiltration outcome to a high posterior while the not-trying remained still pretty unlikely.
Of course, for an obscure small marketplace, the reasoning would happen the other way around: because it starts off more likely to be ignored than infiltrated, silence is golden. I’m thinking of titling any writeup “The Pig That Didn’t Oink”.)
Incidentally, the same argument also applies to Governor Earl Warren’s statement quoted in Absence of evidence is evidence of absence: He can be seen as arguing that there are at least three possibilities, (1) there is no fifth column, (2) there is a fifth column and it supposed to do sabotage independent from an invasion, (3) there is a fifth column and it is supposed to aid a Japanese invasion of the West Coast. In case (2), you would expect to have seen sabotage; in case (1) and (3), you wouldn’t, because if the fifth column were known to exist by the time of the invasion, it would be much less effective. Thus, while observing no sabotage is evidence against the fifth column existing, it is evidence in favor of a fifth column existing and being intended to support an invasion. I recently heard Eliezer claim that this was giving Warren too much credit when someone was pointing out an interpretation similar to this, but I’m pretty sure this argument was represented in Warren’s brain (if not in explicit words) when he made his statement, even if it’s pretty plausible that his choice of words was influenced by making it sound as if the absence of sabotage was actually supporting the contention that there was a fifth column.
In particular, Warren doesn’t say that the lack of subversive activity convinces him that there is a fifth column, he says that it convinces him “that the sabotage we are to get, the Fifth Column activities are to get, are timed just like Pearl Harbor was timed”. Moreover, in the full transcript, he claims that there are reasons to think (1) very unlikely, namely that, he alleges, the Axis powers all use them everywhere else:
To assume that the enemy has not planned fifth column activities for us in a wave of sabotage is simply to live in a fool’s paradise. These activities, whether you call them “fifth column activities” or “sabotage” or “war behind the lines upon civilians,” or whatever you may call it, are just as much an integral part of Axis warfare as any of their military and naval operations. When I say that I refer to all of the Axis powers with which we are at war. [...] Those activities are now being used actively in the war in the Pacific, in every field of operations about which I have read. They have unquestionably, gentlemen, planned such activities for California. For us to believe to the contrary is just not realistic.
I.e., he claims that (1) would be very unique given the Axis powers’ behavior elsewhere. On the other hand, he suggests that (3) fits a pattern of surprise attacks:
[...] It convinces me more than perhaps any other factor that the sabotage that we are to get, the fifth column activities that we are to get, are timed just like Pearl Harbor was timed and just like the invasion of France, and of Denmark, and of Norway, and all of those other countries.
And later, he explicitly argues that you wouldn’t expect to have seen sabotage in case (3):
If there were sporadic sabotage at this time or if there had been for the last 2 months, the people of California or the Federal authorities would be on the alert to such an extent that they could not possibly have any real fifth column activities when the M-day comes.
So he has the pieces there for a correct Bayesian argument that a fifth column still has high posterior probability after seeing no sabotage, and that a fifth column intended to support an invasion has higher posterior than prior probability: Low prior probability of (1); (comparatively) high prior probability of (3); and an argument that (3) predicts the evidence nearly as well as (1) does. I’m not saying his premises are true, just that the fact that he claims all of them suggests that his brain did in fact represent the correct argument. The fact that he doesn’t say that this argument convinces him “more than anything” that there is a fifth column, but rather says that it convinces him that the sabotage will be timed like Pearl Harbor (and France, Denmark and Norway), further supports this—though, as noted above, while I think that his brain did represent the correct argument, it does seem plausible that his words were chosen so as to suggest the alternative interpretation as well.
Surely if BMR had claimed to be seeing law enforcement infiltration I would consider that evidence for infiltration, so how could I turn around and argue that lack of BMR claims was also evidence for infiltration? Yes, this is a good criticism—in a binary context.
So, if BMR had claimed to be seeing infiltration, would you consider that evidence that BMR is not about to be busted?
Yes. If a big market one expects to be under attack reports fending off attack, then one would be more optimistic about it:
Hence, observing BMR silence pushed the infiltration outcome to a high posterior while the not-trying remained still pretty unlikely. Of course, for an obscure small marketplace, the reasoning would happen the other way around: because it starts off more likely to be ignored than infiltrated, silence is golden
(That said, that only applies to the one particular kind of observation/argument from silence; as I told Chen, there were several reasons to expect BMR to be short-lived on top of the general short-livedness of black-markets, but I think the logic behind those other reasons doesn’t need to be explained since they’re not tricky or counterintuitive like the argument from silence.)
Then it seems to me that when responding to “Surely if BMR had claimed to be seeing law enforcement infiltration I would consider that evidence for infiltration, so how could I turn around and argue that lack of BMR claims was also evidence for infiltration?”, you should lead off with “I would consider that evidence for infiltration, but against an imminent bust”, before launching into all the explanation. That way, it would more clear whether you are denying the premise (“you’d consider that evidence for your thesis, too”), rather than just the conclusion. And the phrase “If a big market one expects” would a lot clearer with “that” between “market” and “one”.
No, that would be evidence for it. I know you are trying to show I am having it both ways, but I am not. Think of the full tree of possibilities: ultimatum/no-ultimatum, bluff/real, rational-refusal/irrational-refusal. If real ultimatum had been issued and Saddam had then refused for irrational reasons, that would be strong evidence against the plan, because that’s the situation which is predicted to go well. And that’s the situation Punoxysm thought he’d found, but he hadn’t.
(Actually, you’re the second person today to think I was doing something like that. I mentioned on IRC I had correctly predicted to Gawker in late 2013 that the black-market BMR would soon be busted by law enforcement—as most of its employees would be within two months or so while setting up the successor Utopia black-market—mentioning that among other warning signs, BMR had never mentioned detecting attempts by law enforcement to infiltrate it; someone quoted at me that surely ‘absence of evidence is evidence of absence’? Surely if BMR had claimed to be seeing law enforcement infiltration I would consider that evidence for infiltration, so how could I turn around and argue that lack of BMR claims was also evidence for infiltration? Yes, this is a good criticism—in a binary context.
But this was more complex than a binary observation: there were at least 3 possibilities. 1. it could be that law enforcement was not trying to infiltrate at all, 2. it could be they were trying & had failed, or 3. it could be that they were trying & succeeded. BMR’s silence was evidence they didn’t spot any attacks, so this is evidence that law enforcement was not trying, but it was also evidence for the other proposition that law enforcement was trying & succeeding; a priori, the former was massively improbable because BMR was old and notorious and it’s inconceivable LE was not actively trying to bust it, while the latter was quite probable & had just been done to Silk Road. Hence, observing BMR silence pushed the infiltration outcome to a high posterior while the not-trying remained still pretty unlikely.
Of course, for an obscure small marketplace, the reasoning would happen the other way around: because it starts off more likely to be ignored than infiltrated, silence is golden. I’m thinking of titling any writeup “The Pig That Didn’t Oink”.)
Incidentally, the same argument also applies to Governor Earl Warren’s statement quoted in Absence of evidence is evidence of absence: He can be seen as arguing that there are at least three possibilities, (1) there is no fifth column, (2) there is a fifth column and it supposed to do sabotage independent from an invasion, (3) there is a fifth column and it is supposed to aid a Japanese invasion of the West Coast. In case (2), you would expect to have seen sabotage; in case (1) and (3), you wouldn’t, because if the fifth column were known to exist by the time of the invasion, it would be much less effective. Thus, while observing no sabotage is evidence against the fifth column existing, it is evidence in favor of a fifth column existing and being intended to support an invasion. I recently heard Eliezer claim that this was giving Warren too much credit when someone was pointing out an interpretation similar to this, but I’m pretty sure this argument was represented in Warren’s brain (if not in explicit words) when he made his statement, even if it’s pretty plausible that his choice of words was influenced by making it sound as if the absence of sabotage was actually supporting the contention that there was a fifth column.
In particular, Warren doesn’t say that the lack of subversive activity convinces him that there is a fifth column, he says that it convinces him “that the sabotage we are to get, the Fifth Column activities are to get, are timed just like Pearl Harbor was timed”. Moreover, in the full transcript, he claims that there are reasons to think (1) very unlikely, namely that, he alleges, the Axis powers all use them everywhere else:
I.e., he claims that (1) would be very unique given the Axis powers’ behavior elsewhere. On the other hand, he suggests that (3) fits a pattern of surprise attacks:
And later, he explicitly argues that you wouldn’t expect to have seen sabotage in case (3):
So he has the pieces there for a correct Bayesian argument that a fifth column still has high posterior probability after seeing no sabotage, and that a fifth column intended to support an invasion has higher posterior than prior probability: Low prior probability of (1); (comparatively) high prior probability of (3); and an argument that (3) predicts the evidence nearly as well as (1) does. I’m not saying his premises are true, just that the fact that he claims all of them suggests that his brain did in fact represent the correct argument. The fact that he doesn’t say that this argument convinces him “more than anything” that there is a fifth column, but rather says that it convinces him that the sabotage will be timed like Pearl Harbor (and France, Denmark and Norway), further supports this—though, as noted above, while I think that his brain did represent the correct argument, it does seem plausible that his words were chosen so as to suggest the alternative interpretation as well.
So, if BMR had claimed to be seeing infiltration, would you consider that evidence that BMR is not about to be busted?
Yes. If a big market one expects to be under attack reports fending off attack, then one would be more optimistic about it:
(That said, that only applies to the one particular kind of observation/argument from silence; as I told Chen, there were several reasons to expect BMR to be short-lived on top of the general short-livedness of black-markets, but I think the logic behind those other reasons doesn’t need to be explained since they’re not tricky or counterintuitive like the argument from silence.)
Then it seems to me that when responding to “Surely if BMR had claimed to be seeing law enforcement infiltration I would consider that evidence for infiltration, so how could I turn around and argue that lack of BMR claims was also evidence for infiltration?”, you should lead off with “I would consider that evidence for infiltration, but against an imminent bust”, before launching into all the explanation. That way, it would more clear whether you are denying the premise (“you’d consider that evidence for your thesis, too”), rather than just the conclusion. And the phrase “If a big market one expects” would a lot clearer with “that” between “market” and “one”.