Governing in a democratic political system necessarily involves a degree of incoherence. Coherence is but one among several criteria of good governance in democratic societies, where governments are expected to be responsive to competing interests. Social and political factors bring into play an array of forces that rarely converge toward coherent sets of policies. Interest groups seek to shape public policy in ways which, taken as a whole, serve disparate ends. The information media can mobilise public opinion, and create expectations of quick governmental responses.
Opinion polls bring contradictory short term pressures to bear on longer term policy direction.
Seen in that light, good policy making is less a question of avoiding contradiction than one of managing it. This implies that policy-making systems must increase their capacity to balance and reconcile divergent pressures. No single policy-making system can guarantee improved coherence. Different systems may provide equivalent degrees of coherence with different instruments. How well a particular mechanism functions depends importantly on less tangible factors, such as the political dynamics of the system, the working methods of government leaders, the administrative culture of the civil service, and the nature of the relationships among key actors.