A block veterinary officer reports: 'Not one case of foot-rot has been entered in the block's animal disease register this season. The disease has therefore gone from the block.' The officer's reasoning is most open to criticism because it

A register is a record of reports received, and it can be empty either because there is nothing to report or because there is nobody to report to. With the centre unmanned since June the second explanation is standing ready, and the officer's inference requires that it be ruled out. The number of animals in the block would matter to a rate, and none is claimed; the argument is about one disease and does not need foot-rot to be the only one; and the officer draws his conclusion from this season's blank pages, not from earlier seasons at all.