Regarding Brookline’s ban on plastic shopping bags, Al Lewis writes that the optimal solution is to tax retailers a penny or so per bag — little enough that retailers wouldn’t pass the tax to consumers — and spend that money on conservation measures (“Think of it as an exercise in economics,” Letters, Dec. 2). On the contrary, the solution is to impose a tax large enough that retailers would choose to pass it on, so that consumers would have a direct and clear incentive to avoid plastic bags.
In fact, the optimal solution is to tax both plastic and paper bags, with a higher tax on plastic because of its greater long-term environmental harm, to discourage, but not forbid, the use of throwaway bags.
Unfortunately, towns don’t have the power to impose a tax without the state Legislature’s permission. Since the Legislature doesn’t act, I say good for Brookline for taking what action it can.