with food, or an elderly man’s phlegm when put into a drink. Such things may even cause some people to be overcome by vomiting.

If, however, the effective cause is a specified degree of revulsion, this may be valid, but the dividing line must be established between the degree of repugnance that entails ritual impurity and that which does not. He has not established this. Indeed, demonstrating the repulsiveness of these very substances may undermine the proposed threshold.

Moreover, the degrees of repulsiveness relevant to legal causes and rulings are generally known only through revelation. Thus we say: Whenever a category is ruled ritually impure, we know that its repulsiveness is severe; whenever a category is not ruled ritually impure, we know that its repulsiveness is not severe. We therefore end up inferring from the ruling which degree of the effective cause is legally relevant. Whenever we doubt the ruling, our doubt concerning the effective cause is even greater. This argument therefore fails. As for the evidence establishing its legal relevance, just as it supports repulsiveness in general, it also supports intense repugnance and extreme revulsion.

Second, we say:

Why may the effective cause in the original case not be that it is the urine of an animal whose meat is lawful to eat? This effective cause operates without exception, by the agreement of both ourselves and our opponents in this question. If the converse relationship is not required, our purpose has been achieved. If, however, it is a condition for effective causes, we say concerning it what they said concerning the consistent operation of the effective cause—and with greater justification, since they have been opposed on that point