Here's a nice piece in the NY Times. The article does mention economists agree on many issues, but ultimately divergence arises under very subjective issues. The underlying issue is equality. What's fair? The article talks about taxes in particular. Is making someone pay $10,000 when they earn $100,000 equally as fair as taxing someone $4,000 that earns $20,000? Does it matter how they earn that income? Going beyond how they earn the money, but who's right is it to decide how much we pay in taxes?
We all have different opinions, even among economists. When issues become subjective in nature it is difficult to come to a reasonable solution. This is part of the story behind the current debates over extending the Bush tax cuts.