The president of a village tank committee opposes lining the tank's feeder channel with cement: 'The channel has run unlined for two hundred years and has watered the fields of eleven generations of this village. It should be left as it is.' The president's reasoning is most open to criticism because it

Two hundred years tells us that the channel has been tolerated, not that it is good; a practice endures because nobody has changed it, and that is as true of a bad practice as of a sound one. The president has given the committee a fact about the past where a reason about the present was wanted, and his argument would sound exactly the same if the channel were losing half the tank's water into the sand. The money is a matter he does not raise and, if anything, would be a further objection of his own rather than a fault in the one he makes. The loss into the bed is the figure that would make the case for lining, which is the other side's to establish and not the flaw in the president's step. And whether the generations farmed the same fields is a quibble about his flourish, not about his reason.