The particular observation of no sabotage was evidence against, and could not legitimately be worked into evidence for.
You are assuming that there are only two types of evidence, sabotage v. no sabotage, but there can be much more differentiation in the actual facts.
Given Frank’s claim, there is a reasoning model for which your claim is inaccurate. Whether this is the model Earl Warren had in his head is an entirely different question, but here it is:
We have some weak independent evidence that some fifth column exists giving us a prior probability of >50%. We have good evidence that some japanese americans are disaffected with a prior of 90%+. We believe that a fifth column which is organized will attempt to make a significant coordinated sabotage event, possibly holding off on any/all sabotage until said event. We also believe that the disaffected who are here, if there is no fifth column would engage is small acts of sabotage on their own with a high probability.
Therefore, if there are small acts of sabotage that show no large scale organization, this is weak evidence of a lack of a fifth column. If there is a significant sabotage event, this is strong evidence of a fifth column. If there is no sabotage at all, this is weak evidence of a fifth column. Not all sabotage is alike, it’s not a binary question.
Now, this is a nice rationalization after the fact. The question is, if there had been rare small acts of sabotage, what is the likelihood that this would have been taken by Warren and others in power as evidence that there was no fifth column. I submit that it is very unlikely, and your criticism of their actual logic would thus be correct. But we can’t know for certain since they were never presented with that particular problem. And in fact, I wish that you, or someone like you, had been on hand at the hearing to ask the key question: “Precisely what would you consider to be evidence that the fifth column does not exist?”
Of course, whether widespread internment was a reasonable policy, even if the logic they were using were not flawed, is a completely separate question, on which I’d argue that very strong evidence should be required to adopt such a severe policy (if we are willing to consider it at all), not merely of a fifth column, but of widespread support for it. It is hard to come up with a plausible set of priors where “no sabotage” could possibly imply a high probability of that situation.
The particular observation of no sabotage was evidence against, and could not legitimately be worked into evidence for.
You are assuming that there are only two types of evidence, sabotage v. no sabotage, but there can be much more differentiation in the actual facts.
Given Frank’s claim, there is a reasoning model for which your claim is inaccurate. Whether this is the model Earl Warren had in his head is an entirely different question, but here it is:
We have some weak independent evidence that some fifth column exists giving us a prior probability of >50%. We have good evidence that some japanese americans are disaffected with a prior of 90%+. We believe that a fifth column which is organized will attempt to make a significant coordinated sabotage event, possibly holding off on any/all sabotage until said event. We also believe that the disaffected who are here, if there is no fifth column would engage is small acts of sabotage on their own with a high probability.
Therefore, if there are small acts of sabotage that show no large scale organization, this is weak evidence of a lack of a fifth column. If there is a significant sabotage event, this is strong evidence of a fifth column. If there is no sabotage at all, this is weak evidence of a fifth column. Not all sabotage is alike, it’s not a binary question.
Now, this is a nice rationalization after the fact. The question is, if there had been rare small acts of sabotage, what is the likelihood that this would have been taken by Warren and others in power as evidence that there was no fifth column. I submit that it is very unlikely, and your criticism of their actual logic would thus be correct. But we can’t know for certain since they were never presented with that particular problem. And in fact, I wish that you, or someone like you, had been on hand at the hearing to ask the key question: “Precisely what would you consider to be evidence that the fifth column does not exist?”
Of course, whether widespread internment was a reasonable policy, even if the logic they were using were not flawed, is a completely separate question, on which I’d argue that very strong evidence should be required to adopt such a severe policy (if we are willing to consider it at all), not merely of a fifth column, but of widespread support for it. It is hard to come up with a plausible set of priors where “no sabotage” could possibly imply a high probability of that situation.