Due to my line of work people often ask me for my opinion on the various presidential candidates. A common question that comes up is "who do you think would do a good job?" My initial mental response usually goes something like this: "U.S. presidents have a lot less power and influence than we assume that they do and their ability to do a 'good job' is constrained by a thousand factors that they have no control over. This assumes that we could even agree on what a 'good job' would be because different people have different expectations for what the appropriate role of the president should be." I don't say that out loud, of course, but instead I usually give some standard academic wishy-washy ambiguous "well, it depends" answer. But that's gotten me thinking lately: what does a "good job" constitute for a U.S. president and which 2016 candidates would have a stronger chance of being a "good president"?
The U.S. Constitution is fairly brief on the official duties of the office of the presidency, and thus the expectations and roles have largely developed out of a combination of personality, tradition, and legislation over the last two centuries. It's generally agreed, however, that there are a few specific "roles" that the U.S. president should play.
First, presidents are supposed to ceremonially represent the country that they lead. In this role, they are the "heads of state" and symbolically embody the culture and values of the nation that they represent. Basically, the same skill set is required to do a "good job" in this role as is needed for the Queen of England to do a "good job" in her role: making speeches, attending ceremonial functions, leading the nation through disaster, etc. All you really need is to be a decent human being with some gravitas, level-headedness, an affinity for attending functions and making speeches. A variety of current 2016 candidates could do well here. On the Democratic side, I'd say that Clinton, Biden, O'Malley, Chaffee, or Webb would do perfectly fine in this capacity. On the Republican side, I could also see Bush, Fiorina, Graham, Jindal, Pataki, Kasich, and Rubio as good "heads of state" representing the U.S. in a ceremonial capacity. (Until very recently I would have put Carson on this list as well, although in my mind his surprising rhetoric on Islam disqualified him in this category.)
Second, presidents are expected to be "legislators-in-chief," promoting laws that solve major problems in society. This was not always the case. The American Framers intended Congress to be the chief mover when it comes to lawmaking and it wasn't until the 20th century that presidents became much more active in their roles as primary legislators. Under the last fifteen years the presidencies of both George W. Bush and Barack Obama have shown us just how very difficult it is for presidents to be able to get their way in this era of hyper-polarization and gridlock in the U.S. Congress. Thus, any president will have a very difficult time implementing his or her legislative agenda in this day and age. In my view, the best we can hope for in this category is a president who has extensive prior Congressional experience and a healthy appreciation for the limits of presidential power, as well as a record of participating in legislative compromising (as opposed to, say, deliberately shutting down the government for political purposes). For the record, I doubt very much that anyone would be able to do a "good job" in this category for the foreseeable future. Those that would do at least a little better than dismal might include Clinton, Biden, Chaffee, Sanders, and Webb (all former U.S. Senators, with the advantage going to Biden by a long shot) on the Democratic side and Kasich, Rubio, and Graham on the Republican side.
Third, while U.S. presidents are more constrained in the realm of domestic policy, they have greater latitude in the foreign policy arena where they also serve as commander-in-chief of the military. As is often the case in politics, though, the question of who would do a "good job" in this category depends on one's foreign policy goals, values, and priorities. Putting aside those ideological differences, Clinton arguably has the most foreign policy experience on the Democratic side having served a term as Secretary of State. It's a bit of a mixed bag on the Republican side as most candidates have served as governors or senators specializing in domestic policy, although some senators like Graham, Paul, and Rubio have served on committees where they have developed specializations in foreign policy.
Fourth, presidents are supposed to oversee the vast federal bureaucracy and be "administrators-in-chief." I'm a bit skeptical of the importance of this particular role, though, simply because the president largely delegates these responsibilities to Cabinet officials and staffers. Nonetheless, some current candidates have some executive administrative experience, including Chaffee, O'Malley, and Sanders on the Democratic side and Bush, Christie, Gilmore, Huckabee, Jindal, Kasich, and Pataki on the Republican side. I'd also recommend being wary of claims that business experience is an excellent qualification for the presidency (read Trump and Fiorina).
Fifth, many hope that presidents will be "ideological warriors" who will use their position to represent and fight for a particular cause or to nominate like-minded Supreme Court justices. To some extent I think that those who would do a "good job" as ideological warriors would probably not do as well in the other categories described above, as successful governing often requires the ability to compromise and think in nuance instead of absolutes. The obvious Democratic ideologue is Sanders with O'Malley possibly coming in a distant second. Republicans have an "embarrassment of riches" when it comes to ideologues this year, including Carson, Cruz, Huckabee, Paul, and Santorum.
So where does that leave us? To answer the question of "who would do a good job as president" depends largely on what you think the most important roles of the president are and the degree to which the president actually has any power to meaningfully effect change in those roles, which is often much less than it assumed or claimed in the heat of presidential campaigns.
On balance, I suppose I could recommend Clinton, Biden, or O'Malley on the Democratic side and Bush, Rubio, or Kasich on the Republican side. But I am under no illusions that any potential candidate will be able to deliver on their inevitable promises to bring any substantial change in the way U.S. politics is conducted.