WASHINGTON — In the 2008 Democratic primary, Barack Obama ran against an individual mandate for health care coverage, which his rival Hillary Clinton supported. But Obama then made it the cornerstone of the Affordable Care Act. Donald Trump campaigned on a mythical "tremendous" health care plan that would cost less, offer better care and provide more choices. George W. Bush ran on a "humbler" foreign policy.

The lesson here is not that candidates lie (that's a valid lesson, but one for another discussion). It's that things change, policy proposals don't make it through the legislative meat grinder intact, and quizzing candidates on the details of proposals that will never come to fruition is a waste of time.

That doesn't mean we learn nothing about the candidates from their campaigns. To the contrary, we often know the direction in which they want to head. There was little doubt Obama was going to shoot for some quasi-universal health care plan, that Bush was going to cut taxes and that Trump was going to go after immigrants and dole out tariffs. We knew these things not only because they said them during the campaign, but because these goals were consistent with their past pronouncements and with their current philosophies (to the extent that they had them).

Instead of quizzing, say, U.S. Sen. Elizabeth Warren, D-Mass., on how she is going to pay for "Medicare-for-all," it would be far more productive to examine her record for how, if at all, she compromised to achieve aims; the degree to which she has favored regulation of sectors of the economy and in what circumstances; and — this is critical — why she thinks Obamacare cannot be fixed. I'd like to hear answers to those questions, as well as:

• If Democrats do not have the House and a filibuster-proof majority in the Senate, what changes in the existing health care system would you seek to make? How do you entice Republicans to accept an expansion of guaranteed health care?

• What are the problems with the Affordable Care Act you think need to be fixed?

• What are your priorities in improving health care: Expanding Medicaid? Reducing health care costs for the middle class? Reducing drug prices?

• What are the downsides to what you are proposing?

In other words, it is far more important to understand what candidates' values are, what their thought processes are, how adept they are at compromising, how well they understand the topic and whether they have enough self-awareness to understand that what they draw up in a policy paper has to work in the real world.

Similarly, foreign policy, we can predict, is likely to get short shrift in the Democratic primaries. We will find it even more difficult to parse out the candidates' foreign policy views and gauge what we might expect from them. (Remember Bush's "humbler" foreign policy?) Here, too, we'd do better to assess their values, priorities and approach to big issues than demand specific answers on issues that may be in the rearview mirror by the time they get elected. I'd like to hear answers to these questions:

• What interests do we have in the Middle East?

• Even if you were against the war in Iraq, what considerations now come into play before we withdraw troops?

• North Korea is proceeding with its missile program, from what we see in the media. We've tried bluster, and we've tried negotiation. Should we consider reducing our demands that Pyongyang denuclearize entirely? Would you meet face to face with Kim Jong Un?

• Russia still occupies territory of a sovereign Ukraine, to whom we gave pledges of defense when it gave up its nuclear weapons. Post-Trump, how should we approach a country that has occupied its neighbors, has committed war crimes in the Middle East, has interfered with our election (and those of other Western democracies), and has repressed its own people?

• What is the connection between hard and soft power?

In sum, this time around, we had better test the candidates' intellect, values and knowledge, lest we wind up with another totally unqualified commander in chief. If we ask smarter questions, we might get smarter presidents.


Rubin is a Washington Post columnist.