President Obama’s plan to give a major economic speech after Labor Day means that, finally, Washington is going to have a serious conversation about creating jobs. And it can't come a moment too soon. While Thursday's stock market decline shouldn’t alarm you, the conditions that sparked it should.

Of course, whether that conversation on jobs leads to action on jobs is more a question of politics than policy. Republicans want no part of anything with Obama’s name on it and, until that changes, very little can pass Congress.

Still, the best policy conversations start with what we should do, not with what we can (or can’t) do. And it’s not like we have to think too hard about ways of boosting growth: Infrastructure projects, direct aid to the states, assistance for the unemployed, and other familiar remedies should work just fine. As Josh Bivens of the Economic Policy Institute noted recently,

There are not many new and exciting policy levers that can be pulled by Congress and the president to solve today’s unemployment crisis. Fortunately, the old (and presumably boring) policy levers could reduce unemployment much more quickly if applied with enough force.

The key is finding the right mix of these ideas and getting the details right. With that in mind, here are three essential elements of a successful jobs agenda, based on conversations with a series of economists -- mostly center to left -- who can speak to this issue with way more authority than I can.

Size. This one can be said very simply. The jobs program should be big.