The net welfare effect of congestion pricing, including its distributional impact, is positive on the condition that revenue is recycled into transit and targeted relief and that exemptions stay narrow; it is not automatically equitable by design.
By reducing zone traffic, cordon congestion pricing causally produces cleaner air, fewer crashes and traffic deaths, faster transit and freight movement, and a large stream of dedicated revenue.
Distributional analyses (RAND; UC Institute of Transportation Studies) find ultimate incidence depends on revenue use: recycling into transit and rebates makes the package net-progressive, because lower-income residents disproportionately ride transit and bear the pollution that falls, and NYC's air-quality gains were largest in dense corridors.
A flat toll is regressive at the point of payment: it takes a larger income share from lower-income drivers, some of whom lack good transit alternatives, which is the standard and legitimate equity objection.
Could a different cause produce the same effect E in this case?
Is there a plausible causal mechanism by which C could bring about E?
How strong is the causal generalization linking C to E? Are there documented cases where C does not produce E?
Are there intervening or confounding factors that could interfere with the causal chain from C to E?
Is the apparent link between C and E merely a post hoc correlation rather than a causal relation?