The Island of Truth and Lies, Part IV

(See Parts I, II & III before reading on)

Part IV: An Honest Chief

Anyone who has tried to replicate the studies of other anthropologists knows that anthropological works are often riddled with errors.

That observation became prominent in the logician's mind as he gradually gathered information from the tribesmen who came and went from his cell with careful and precise questions. As far as he could tell, every one of them proved honest. And every one who he asked about his fate assured him that they were sure that they would find him delicious.

At first he suspected that he might have been captured by some strange mix of liars and truthtellers, cannibals and welcoming natives. But by the time that the chief came to see him, he had cut through this strange mix to identify a simpler explanation for his situation: he was surrounded by honest cannibals. Thinking back over all of the primary and secondary sources that he had studied diligently back on the mainland, he realized that he may have been a bit too comfortable accepting that the tribe of liars were the cannibals and that the honest tribe would be welcoming.

When the chief came in the anthropologist froze up, nervous about his fate and hesitant to use up his one question. But the chief, a gregarious and polite man, assured him that, unlike his tribesmen, he would be happy to answer questions for a while. The logician questioned him until he was satisfied that the chief was honest, and learned in the process that this chief had never met an anthropologist before, for he never left the village. He had, however, heard plenty of reliable reports about them, and so in order to be sure that our anthropologist was satisfied he had let himself be put through this questioning before explaining the situation.

After the amateur logician had learned about the chief and told the chief a little bit more about himself (at the chief's request), the chief felt that they were now comfortable enough together to get down to business. He explained to the anthropologist, in no uncertain terms: the tribe is going to eat you in the near future. That, he said, is a fact, and there is no sense in denying it. They would get along much better if they could work from this shared assumption.

The only questions remaining were when and how. The timing issue would be decided by the tribe, but, as a cordial host, the chief would let the anthropologist help him decide on the preparation. The anthropologist sat there nervously, as the chief laid out details that he had refused to even imagine when he had been piecing together the truth before meeting with the chief.

Some members of the tribe liked stew with boiled logician, while many others preferred their logician roasted over an open fire. A few liked more exotic preparations, which were significantly more unpleasant to undergo. But, assuming that the anthropologist remained sensible and cooperative, they were not something that he needed to be concerned about.

It was up to the anthropologist to decide whether he would be roasted or boiled. Leaving this decision to the guest was not just a kind gesture, the chief explained, it was also a way of helping keep peace within the tribe and avoiding the kind of conflict that could result when some people within the tribe made a decision for the whole tribe that other tribespeople did not like.

The way that the anthropologist would indicate his decision was by making one statement. If it is true, the chief told him, then you will be roasted, and if it is false then you will be boiled. Your statement must be a proposition. I must be able to ascertain whether your statement is true or false within the near future. Do not remain silent, do not say something that is neither true nor false, and do not make some obscure statement that I cannot assess. If you prove uncooperative and fail to make a verifiable propositional statement, then those alternative preparations will become more relevant to you. I will consider your next statement to be the proposition to assess.

The poor anthropologist fell silent for a minute. Not eager to rush into the pot of boiling water or the bonfire, he decided to first risk one question: is my decision just between being boiled alive and being roasted alive?

There is more to it than that, the chief replied. One guest, for instance, decided that he would like to be roasted if it was raining while he cooked, but boiled otherwise. So he told me: it will be raining when I am cooked. We ended up roasting him on a cool, rainy evening.

But that is enough reminiscing. It is time for you to make your statement.

The clever anthropologist was ready to give his proposition. He did not want to be boiled or roasted, and he certainly did not want to undergo any alternative preparation. So what did he say?

Continue to Part V: Out of the Boiling Pot, Out of the Fire