The private sector never has been and never will be up to tasks like that. Even in the bygone heyday of Bell Labs, corporate investment was alongside, not in place of, government investment. Today, the scope, duration and cost of breakthrough research is either beyond the private sector’s corporate and philanthropic resources or outside its profit model. A salient point in “The Entrepreneurial State,” amplified in a review by Martin Wolf, the chief economics commentator of The Financial Times, is that corporations today often spend surplus cash on share buybacks rather than on fundamental innovation.

In brief then, it is an essential role of the federal government — in the interest of tomorrow’s prosperity — to invest and engage in scientific and technological discovery. And it is a role the government has played well, until now. After rising steadily for decades, federal financing for research and development peaked in 2009, at $165.5 billion, bolstered by that year’s stimulus spending. It has since sunk to levels last seen almost a decade ago, falling to $133.7 billion this fiscal year.

That roughly $32 billion drop is even greater when adjusted for inflation, and it encompasses both defense- and nondefense fields, including health, energy, the environment, climate, technology and electronics. One key area, basic science, received about $40 billion in the peak year 2009. Since then, it has fallen, to $30 billion last year, one of the sharpest declines ever. The future does not look much brighter. Constrained by austerity-induced budget caps, the research and development budget recently proposed by President Obama for fiscal year 2015 was only $135.4 billion, the lowest request of his presidency. Chances for more money on top of the budget caps, as Mr. Obama has called for, are virtually nil. And given that Congress invariably enacts less than the president asks for, the trend is all downhill.

Worse, the direction is unlikely to reverse as long as prevailing rhetoric reinforces the notion of an inefficient government sector versus a dynamic private sector. To win budget battles going forward, Democratic policy makers and administration officials must also win the debate in favor of entrepreneurial government. The fact that they have not successfully made that case in recent years is a result of both implacable Republican opposition and their own tendencies to exalt the private sector while ignoring its many roots in public spending.

Correcting that misimpression is crucial to building and sustaining support for public involvement in science and technology. Equally important is developing ways to ensure that taxpayers share in private-sector profits that ensue from government efforts. Fair and adequate corporate taxation is the obvious way, but that is currently a political non-starter. Non-tax models also need to be considered — for instance, requiring recipients of federal grants to pay a portion of subsequent profits to the government or establishing a federally backed innovation fund that lets the government retain an equity stake in companies that use the fund.