Christopher Ingraham of Wonkblog points out that a new Pew Research Center survey shows that most of the public is ignorant about the distribution of federal spending. Only 20% realize that the federal government spends more money on Social Security than on foreign aid, transportation, and interest on the government debt. Some 33% believe that foreign aid is the biggest item on this list, even though it’s actually the smallest. It accounts for only 1% of the federal budget, compared to a whopping 17% for Social Security, which is one of the biggest federal outlays and has been for decades.

The Pew poll is consistent with numerous previous studies that reach similar results, consistently showing that the public massively overestimates foreign aid spending, and underestimates spending on big entitlement programs, such as Social Security and Medicare. British voters are misinformed about their own government’s budget in much the same way.

Ignorance on this point has a significant influence on politics and policy. A large percentage of voters implicitly assume that we can solve the federal budget crisis simply by cutting unpopular foreign aid programs, without raising taxes or touching entitlements. That makes it politically difficult to address our looming fiscal crisis (in which Social Security and other entitlements are major factors) in a realistic way.

Public ignorance about the budget has persisted despite extensive public debate over our fiscal problems in recent years, and despite the fact that accurate information about the distribution of federal spending is readily available on the internet and elsewhere. The same goes for many other basic facts about government and public policy that most of the public is ignorant of. Ignorance has persisted despite the growth of new media, increasing education education levels, and even rising IQ scores.

The problem is not that the public is stupid or that information is unavailable, but that for most voters it is actually rational to pay little attention to political issues. No matter how well informed you are about the federal budget and entitlements, the likelihood that your knowledge will actually influence policy is miniscule, because there is so little chance that your vote will ever decide an electoral outcome. That reality makes it extremely difficult to overcome political ignorance by increasing public knowledge through education, improving media coverage of political issues, or other oft-proposed remedies.

Sadly, public ignorance about federal spending is unlikely to diminish greatly anytime soon. It will continue to have harmful effects on fiscal policy. That may be a good reason to put fewer of our resources under the control of the federal government in the first place.