RIght vs Left

I came across a very good post on "right vs left" on economic matters ....http://gregmankiw.blogspot.com/2007/12/how-do-right-and-left-differ.html .

Mr Greg Mankiw lists some of the differences in the right and left thinking and how does this finally lead to espousal of bigger/smaller government on two sides. Basically from an intellectual point of view, there is a marginal social cost of government intervention in any affair which shall be greater than the positive externality or less than the negative externalities out of government action. If this is the case, the govenrment action is fruitful else it is not. Both the left and right agree on this. The quarrel between the two sides is that the calculation of these costs since these calculations are not straightforward and brings in assumptions and time period which are debatable. Hence we have a situation where the two sides though agree on the common intellectual principle have different manifestations of the application of principle hence arriving at separate conclusions causing disagreements.