America used to be a country that built for the future. Sometimes the government built directly: Public projects, from the Erie Canal to the Interstate Highway System, provided the backbone for economic growth. Sometimes it provided incentives to the private sector, like land grants to spur railroad construction. Either way, there was broad support for spending that would make us richer.

But nowadays we simply won’t invest, even when the need is obvious and the timing couldn’t be better. And don’t tell me that the problem is “political dysfunction” or some other weasel phrase that diffuses the blame. Our inability to invest doesn’t reflect something wrong with “Washington”; it reflects the destructive ideology that has taken over the Republican Party.

Some background: More than seven years have passed since the housing bubble burst, and ever since, America has been awash in savings — or more accurately, desired savings — with nowhere to go. Borrowing to buy homes has recovered a bit, but remains low. Corporations are earning huge profits, but are reluctant to invest in the face of weak consumer demand, so they’re accumulating cash or buying back their own stock. Banks are holding almost $2.7 trillion in excess reserves — funds they could lend out, but choose instead to leave idle.

And the mismatch between desired saving and the willingness to invest has kept the economy depressed. Remember, your spending is my income and my spending is your income, so if everyone tries to spend less at the same time, everyone’s income falls.