Group Behavior in “Individual” Politics: Fluid Dynamics Explains Why Some Succeed and Others Fail

May 31, 2024   Robert Gmeiner

  • Group Decision Making
  • Blog

Voting is individual, both when the people vote for representatives, and when representatives vote on legislation.  Although formalized rules center on the individual, groups really do matter.  People identify with political parties and with causes they like.  In the legislature, caucuses form, but legislators also trade votes with each other to get what they want.  Thus, voting is not simply a matter of “yes or no” on any individual bill.  An environment of multiple issues and diverse opinions is ripe for strategic behavior.  Legislators need to consider far more than their own opinions and desires when they interact and vote.  From there, it logically follows that pressure groups need to be strategic as they try to exert political influence.

How do groups behave? And why are some more successful in politics than others? 

Public choice theory has long emphasized that some policies have concentrated benefits and widely dispersed costs, so those who benefit can spend more to lobby.  A classic example is the sugar tariff that benefits a few well-connected families and costs millions of people a few dollars each.  This is simple and intuitive, but very incomplete.  After all, there are many hypothetical policies with concentrated benefits that don’t get enacted.  Conversely, some programs have benefits that are more dispersed than the costs, like food stamps and Medicaid.

A complete theory must explain why some political groups succeed and others fail.  To develop this theory, I turn to the theory of fluid dynamics for metaphorical reasoning in my recent piece “The Dynamics of Dominance and Compromise,” which was recently published in DECISION.  Fluids are groups of molecules, but their behavior depends on characteristics of the fluid, or group, not on the molecules.  Consider water, the simple molecule H2O.  It can exert great force as an ocean wave, or it can be an atomized spray from a garden hose.  The same volume of water in a river can be a smooth flow or dangerous whitewater rapids, all without changing its chemical properties.

The behavior of fluids depends on the size, speed, and temperature of the flow.  This recently published paper develops analogies between the characteristics of groups and fluids.  By looking at how well fluids can mix with other fluids or permeate the surface of another, these analogies can predict which group will “win” in the political arena.  As it turns out, concentrated benefits and dispersed costs can be useful in predicting whether a group will get its preferred policies enacted.  What matters more is the narrowness of the group’s policy focus, the size of the group, the extent to which its members are committed to the cause, and the degree to which policymakers are already amenable to its actions.  Strength in one of these areas can compensate for what is lacking in others, but no single characteristic will be good enough on its own to guarantee political success.

This fluid dynamics framework is a new, useful way to think about political pressure groups.  Far from negating earlier theories, it can unite them.  For as long as policies are made by groups, like legislatures and the subgroups within them, there will be group behavior that depends on the characteristics of the group.  Individuals who want to succeed will need to find ways to do so within groups, so this framework can also be thought of as a framework for organizing for political success.

Read the Abstract or Full Paper >>