What this means is that the revenue from any new taxes on pollution could be used to reduce other taxes, such as Social Security contributions or the income tax (but not, of course, the capital-gains tax).
Social Security contributions or the income tax could be reduced by a new tax on pollution.
mnli hypothesis: Social Security contributions or the income tax could be reduced by a new tax on pollution. premise: What this means is that the revenue from any new taxes on pollution could be used to reduce other taxes, such as Social Security contributions or the income tax (but not, of course, the capital-gains tax).