An Inaugural Address is a new president's best opportunity to put forward a vision of government. In 1965, Lyndon B. Johnson proposed an expansion of the federal role to counter economic and racial injustice. "In a land of great wealth, families must not live in hopeless poverty," he declared. In 1981, Ronald Reagan called for a rollback of Johnson's Great Society: "It is time to check and reverse the growth of government which shows signs of having grown beyond the consent of the governed."

Reagan didn't really make the federal government smaller, but he did check its growth. Every president since has searched for some way to tackle problems without making government bigger. In 1989, George H.W. Bush exhorted voluntarism, or as he put it, "a thousand points of light." In 1993, Bill Clinton proposed a new social compact in which government would "offer more opportunity to all and demand responsibility from all." In 2001, George W. Bush reprised his father's theme of altruism, noting that "compassion is the work of a nation, not just a government."

In 2009, looking out over the largest crowd ever assembled in Washington, D.C., Barack Obama framed the issue in terms of simple efficacy. "The question we ask today is not whether our government is too big or too small, but whether it works—whether it helps families find jobs at a decent wage, care they can afford, a retirement that is dignified," he said. "Where the answer is yes, we intend to move forward. Where the answer is no, programs will end."

This view is in keeping with Obama's non-ideological approach to politics. To most of those listening, it came across as an expression of our new president's unsentimental good sense. Yet on rereading the speech in the less euphoric light of the next day, that passage seemed insufficient as a governing philosophy. "Whatever works" is less a vision of the public sector's proper role than a placeholder for someone who has yet to figure out what he thinks that role should be.

Obama's pragmatic liberalism risks blurring execution with intention, means with ends. To take his illustrations, it is either up to the commonweal to provide a minimum income to retired people, to offer health insurance to everybody and to increase income equality—or it isn't. Most liberals would say these are legitimate responsibilities of government. Most conservatives would argue they aren't. On income security for the elderly, we've had a social consensus since the New Deal. On health care, a consensus may be emerging after decades of national ambivalence. When it comes to growing income inequality, a newer problem, there is no consensus. But Obama must decide what government's goals are before considering the subordinate questions of what works and how much we can afford.

Obama's vagueness about the federal role comes at a moment when clarity is especially needed. Our government is about to become bigger, more powerful and more expensive in order to deal with a sprawling economic crisis. Washington will take on responsibilities it hasn't shouldered in 75 years, such as directly alleviating unemployment and perhaps nationalizing banks. Many who would ordinarily reject such interventions on principle can justify them as misery relief, Keynesian stimulus or emergency management. But some see in the expansion something further-reaching—a redefinition of the government's relationship to markets transcending the current crisis.