Pythagorean said:
Why don't you support them? At least, statistically, you don't. If you do, then I'm equally interested in hearing why you support them. I find myself agreeing with them on a lot of the issues the more I look into them.
The way I see it, politics is divided between the micro and macro view - the local and the global in terms of spatiotemporal scale in systems-speak. And Green/Left/Conservative policies sound right because they address the long-term, society-wide, view, while Liberal/Right policies sound correct also because they address the short-range, personal view.
So you have the eternal problem of two poles for policy - a global stress on the need for stabilising co-operation, and a local stress on the need for creative freedoms - and the struggle is to find a party with a political model that balances both these natural tensions.
Green politics is well-developed where I live - New Zealand - and with proportional representation, Green MPs have 12% of the seats in Parliament.
But the Green Party arose out of progressive roots and so has the problem that much of its base thinking is well to the left in terms of local economic freedoms. But as a new younger generation is taking over, a better balance is emerging.
We also have here the emergence of the "blue-green" movement. So that is a version of green policy coming from the neo-liberal side. And there are ministers in our current right-of-centre government that have been champions of it. Even our major business lobbies have rebranded themselves to endorse sustainability as a political philosophy -
http://www.sustainablebusinessnz.org.nz/news-and-info/executive-insight
Again, as green politics matures, there is a balancing of the needs for global social collaboration which gives you your long-term policies, and the equal need to foster local individual creativity, which is the focus of the short-term policies.
So from a political theory point of view, there is some really interesting thinking here about how to be green in a practical sense. The debate has moved a long way from the preachy do-gooders towards a rational and evidence-based approach.
Unfortunately, being a small country afloat in a large and turbulent world, NZ has very little chance to put good ideas into effect. For instance, we created a "Rolls Royce" emission tradings scheme because it seemed the world might take carbon gases seriously. But that has been put on ice effectively because the world isn't ready for action.
Anyway, my point is that "green" politics will fail if it is just about the global constraints on individual action (even if those constraints are necessary in a finite world). Any political system that is too one-sided is going to fail - neo-liberalism, with its entire focus on local freedoms, is another example.
But it is quite possible to design political structures that aim to get the best of both worlds - maximising intelligent behaviour both at the local and global levels of society. And green politics is based on the recognition that there are indeed hard global limits, in terms of ecology, resources, population, climate change, peak fossil fuel, etc, which have become a necessary part of political decision making.
Of course, I can already hear the immediate response - human technological ingenuity means there are no environmental limits in fact. We can invent our way out of any corner.
Again, a true green political model would acknowlege this localised creativity. A green system would of course want to maximise our ability to invent our own futures. But green politics remains rooted in a systems view where the local and global have to go hand in hand. Neither a complete shut-down on consumption, nor a complete trusting to ingenuity, are an answer. However that still leaves the very real problem of designing a political system that can deliver the appropriate balance of behaviours in a society.
The polarities may define the extremes that constitute the system, but the system itself is about the functional interaction of these extremes. So rather than voting for the extremes, you want the opportunity to vote for the healthy functioning of the system.