The supercommittee's failure to reach an agreement on debt reduction will probably result in unexpected reductions of the U.S. nuclear arsenal. That possibility concerns the defense establishment, but it also presents an opportunity: It might finally be possible to have an honest debate about the role of nuclear weapons in U.S. strategy and the prospect for further arms reductions.

Before moving ahead with this conversation, though, it is critical to review and debunk three misguided ideas about nuclear weapons.

The first is that our nuclear world is safe and stable and that all we need to do now is prevent other nations from acquiring nuclear weapons. Though it is undoubtedly true that the U.S. stockpile is safer than ever, the dangers are far from over. Nuclear terrorism remains a threat. Mistakes are possible, too. In just one example, in August 2007, six nuclear warheads disappeared for two days between North Dakota's Minot and Louisiana's Barksdale Air Force bases.

What's more, unsafe nuclear weapons elsewhere remain a major threat. Tensions between nuclear India and Pakistan, the security of the Pakistani nuclear arsenal and the future of the North Korean nuclear weapons program all suggest that the commitment to making U.S. weapons more reliable and secure will not solve the problem.

The second piece of nuclear mythology is that nuclear disarmament has never taken place and never will. Put slightly differently, it is the idea that nuclear history is proliferation history. But nuclear disarmament is far from unprecedented. South Africa, Ukraine, Belarus and Kazakhstan all disarmed. Many nuclear-capable states chose to pursue security without nuclear weapons because policymakers recognized these weapons would endanger rather than protect them. Sweden went down the nuclear path and then decided against it in the late 1960s.

Germany had a nuclear weapons program during World War II but became a law-abiding, non-nuclear member of the Non-Proliferation Treaty. Japan had two nuclear weapons programs during the war and accumulated a significant quantity of plutonium; since then, its authorities thought about restarting a weapons program four times but decided against it.

In each of those cases, most analysts did not believe that giving up nuclear weapons ambitions was possible. They were wrong, and today we all are glad these countries chose the path they did.

The third misguided concept is that reducing the size of the U.S. nuclear arsenal will lead to proliferation. Those who believe this think that countries that no longer feel protected by U.S. nuclear weapons will start building their own to protect themselves. Although this might have some validity, it should be assessed on a case-by-case basis.

Historically, many of the states that have disarmed or given up their nuclear-weapon ambitions - including every non-nuclear nation outside of NATO - have done so despite the absence of a nuclear-security guarantee.

On the other hand, states determined to get the bomb, such as the United Kingdom and France, have done so despite security guarantees. Finally, this argument assumes that the role of nuclear weapons in future alliances and geopolitical relationships will be as important as it was in the past. This might be true, but it cannot be considered a fact. It is just a bet on the future and a set of policy priorities.

In 2007, "the four horsemen" - Henry Kissinger, Sam Nunn, William Perry and George Shultz - wrote a highly influential opinion piece in the Wall Street Journal arguing that relying on nuclear weapons for the purpose of deterrence has become "increasingly hazardous and decreasingly effective." Coming from former Cold Warriors from both sides of the political aisle, it legitimized the goal of a world without nuclear weapons and challenged the conventional wisdom.

Now policymakers in Washington and candidates on the electoral trail should embrace the issue, and begin a real conversation with the electorate about the role of nuclear weapons in U.S. policy rather than allowing that policy to be driven by inertia or budget cuts.