Six months before he was assassinated, John F. Kennedy gave a speech at Vanderbilt University in which he declared that "only an educated and informed people will be a free people," and "the ignorance of one voter in a democracy impairs the security of all."  If these precepts are true, the results of a groundbreaking poll show the United States is in grave danger.

To determine what voters understand about policy issues, Just Facts, the research institute of which I am president, commissioned a scientific nationwide poll of people who say they vote "every time there is an opportunity" or in "most elections."  The poll consisted of 20 questions, one concerning voters' political leanings and the rest dealing with their knowledge of policy issues.

The policy questions covered an array of issues, including health care, hunger, government spending, the national debt, taxes, pollution, global warming, energy, and Social Security.  Each question addressed a central aspect of each issue, and poll respondents were provided with true/false or multiple-choice options.

Disappointingly, a majority of voters gave the correct answer to only four of the 19 questions, even though the factual gap between the right and wrong answers was sometimes enormous.  For example:

• Only 4% of Democratic voters and 31% of Republican voters knew that the top 1% of income earners pay a higher average federal tax rate than the middle class.  Data from the Congressional Budget Office shows that the upper 1% pays an average federal tax rate 2.5 times higher than that of the middle class.

• Only 18% of Democratic voters and 58% of Republican voters knew that the federal government spends more money on social programs (such as Medicare, education, and food stamps) than on national defense.  Roughly 60% of federal spending is for social programs and 20% is for national defense.

• Only 28% of Democratic voters and 41% of Republican voters knew that the air in the United States is less polluted than it was 30 years ago.  EPA-measured levels of criteria air pollutants and hazardous air pollutants have fallen considerably over this period.

The above results reveal greater levels of ignorance among Democratic voters, but Republican voters fared worse on other questions, such as the following:

• Only 23% of Republican voters knew that the Earth is generally warmer than it was 30 years ago, while 74% of Democratic voters answered this question correctly.  Both satellite measurements and ground-level thermometers show that the earth's average temperature has noticeably increased since 30 years ago.

• Only 10% of Republican voters and 37% of Democratic voters knew that Social Security's financial challenges do not stem from politicians looting the Trust Fund.  In fact, the term "looting" is a misnomer, and Social Security's fiscal problems are the result of factors such as increases in life expectancy without a comparable increase in the retirement age, the higher birth rate of the baby-boom generation compared to following generations, and the increasing number of people receiving disability benefits.

While voters bear responsibility for educating themselves, such glaring disconnects between perception and reality go far beyond voter apathy or inattentiveness.  As our institute has repeatedly documented, in addition to deceitful rhetoric spread by politicians and commentators, the public is also misled by journalists, educators, advocacy groups, think-tanks, and fact-checkers.  Collectively, this produces a caustic flow of disinformation that undermines informed decision-making in our elections, institutions, and personal lives.

If President Kennedy was right, our nation will invariably decline unless more Americans make principled commitments to find the truth, speak it, and hold to account those who distort it.  We should guard the truth with as much vigilance as our personal property, for when misinformation is spread – whether out of naiveté or dishonesty – the end result is the same: an electorate steeped in falsehoods that erode our liberty, threaten our security, and damage our economy.

James D. Agresti is the president of Just Facts, a nonprofit institute dedicated to researching and publishing verifiable facts about public policy.