I sort of think you have it backward. Policy is about realizing vision. And vision is much more philosophical and emotional as it is rational. Going back to America's founding, the central conflicts were between the urban, strong central government, pro-banking leaders, and the agrarian, decentralized, states-rights proponents (exemplified by Hamilton on the one hand and Jefferson on the other). This conflict led to the formation of the first political parties (the Federalists and the Democratic Republicans), even though not half a decade previous, pretty much every agreed that "factions" were to be avoided. There's no amount of data or rationality in the world that can tell us whether we should be cosmopolitan or agrarian. Only our personal philosophy or belief system can inform that. What data can do is to help us realize our goals once we have set them.

My stance that environmental policy should rise above partisanship is based on my belief that it's in everyone's interest to tackle large environmental problems (which we have been able to do in the past several times). Most issues don't lend themselves to this, because most issues are existential in nature. It used to be that politicians had saying that politics ends at our borders. This was in recognition of the fact that America's adversaries represented existential threats and we all agreed that we needed to present a united front to the world--it derives from the philosophical belief that the American project is worth protecting no matter our internal divisions (that's the policy vision--how it's prosecuted is where we need the data).

I think that partisan politics serve a very important purpose (giving voice to the voiceless--they're the labor unions of policy). It's easy to look at our current political climate and conclude that partisanship is the problem. I don't think it is per se. I think that the problem is large and multi-faceted, and that the hyper-partisanship is a result not a cause of our problems (I think most of our problems drive from bad finance, but that's a bigger topic than I can elaborate here). If anything we need more vision, not more data. Data are the easy part.