The subjects of every state ought to contribute towards the support of the government, as nearly as possible, in proportion to their respective abilities; that is, in proportion to the revenue which they respectively enjoy under the protection of the state.Of course, many self-declared fans of Adam Smith like to decry "taxation as theft," quite contrary to the spirit of their icon, but also forgetting their pet piety that "there ain't no such thing as a free lunch." After all, taxes are the price paid for a civilization that has a workable concept of theft as a criminal offense for these libertopians to misconstrue so glibly in the first place.
Those who stamp their feet and demand to know "just who do you expect to pay?" for welfare support for those people momentarily marginalized by misfortune from contributing their potential measure to commonwealth -- these people are always forgetting that those who succeed sufficiently to tax, and those who are thriving for now, all depend, indispensably if not entirely, for good their fortune on the efforts of the diversity of their contemporaries and on a vast ritual and material infrastructure arising from a shared past and ongoing collaborative maintenance.
From those to whom much is given in this shared enterprise, much is rightly expected in its support. For those who grasp the ineradicable fact of their interdependence on their fellows there should be no resentment at the expectation of their contribution to the maintenance of a world that works and has worked so well for them.
Steeply progressive taxes are a countervailing power to the otherwise inertial concentration of wealth that always undermines the equitable distribution of information indispensable to a meritocratic assignment of effort in the service of the solution of shared problems and which also always undermines the equitable access to governance and law indispensable to democratic participation and accountability. Further, steeply progressive taxes are necessary to administer public and common goods in the public interest and circumvent their private violation and abuse, as well as to fund the constellation of general welfare provisions of health, education, income security which ensure that the scene of consent to the terms of everyday commerce is reliably informed and non-duressed without which "free enterprise" is always a rationalization for abuses and vestigial enslavement.
In other words, far from representing the violence of "theft" taxes provide for the legal adjudication of disputes, for the maintenance of the scene of informed, non-duressed consent and for the equitable administration of public and common goods of which non-violence chiefly actually substantially consists.
Adam Smith did not grasp all of these connections as clearly as we have come to do ourselves after centuries of plutocratic industrial and financial and military abuses -- not to mention centuries of convulsive efforts to ameliorate avoidable human suffering and facilitate prosperity through social democracy -- but he certainly grasped the issues at hand incomparably more clearly than the Republicans and Randroids who love smugly to misquote without reading him.