It doesn't even matter that first part because we have a->b&c. If c is that it doesn't harm any portion of the population, then it doesn't matter what b is because c is already false. And if c is necessary for a (that it is acceptable to use) to occur, and c does not occur, then a cannot occur.
It doesn't even matter that first part because we have a->b&c. If c is that it doesn't harm any portion of the population, then it doesn't matter what b is because c is already false. And if c is necessary for a (that it is acceptable to use) to occur, and c does not occur, then a cannot occur.