Science is based on skepticism not dogma. There are problems with models and data sets. The models have not been particularly accurate with historical or current data. A bigger problem is the extent, quality, and completeness of the data sets. The problem is our current data sets do not have any indication of longer term cycles of century and millennia length. Through solar variability (Maunder minimum and the Little Ice Age) and the actual human effects are murky.
My personal objection to basing policy on the CAGW is what if it is proven false? Many of the goals can stand on their own right as we should be trying to leave the environment in better shape than we found it. Thus reducing one's carbon foot print, lessening one's overall impact, etc. are good personal objectives.