Veto Players. Veto player. Veto players are individual or collective actors whose approval is necessary to change the status quo In political systems we have Institutional veto players: parliamentary assemblies, constitutional courts etc. Partisan veto players: government coalition parties
W(SQ) for the three VPs is the colored area closer to the three ideal points than the SQ
If W(SQ) is empty, the political system does not allow reform
Winset of the status quo is a more reliable proxy of the real policy stability. When the winset is very small it is highly likely that not policy change takes place because of the transaction costs. The size of the winset tell us also if we are dealing with an incremental change or a major policy change.
Unanimity core is a measure independent of the position of the status quo. Sometimes is not easy to locate the status quo. Moreover political analysis based upon status quo position has an extremely contingent and volatile character. If you want to assess some stable and general features of the political systems unanimity core is the best measure.
With three VP, the triangle is the core and the orange area the winset
A new veto player D increases the core ... And decreases the winset
…However for some specific status quo the new veto player can be outside the unanimity core and not affect the policy stability.
The size of the Winset of SQ, W(SQ), is a necessary but not sufficient condition for having a (big) policy change (|SQ-SQ’|). If the Winset is small the change will be small (or absent). If the Winset is big the change can be big or small (or absent). However on average the size of the change should increase with the size of the Winset.
X’ is unanimously preferred by A and B to x. The line between A and B is
A Pareto set (or Unanimity Core)
Previous picture helps to illustrate that the control of agenda is important also when there is not instability (a cycle) and the voting rule is the unanimity rule. Two political actors and 5 alternatives; if A controls the agenda he can win B1
If the agenda setter was more centrally located as regards the other veto players, it could choose best alternatives (and sometimes even its idela point) as Z, that is insed the winset of A and BAgenda setting power, number of veto players and location in the political space
if X has agenda setting power
and A is the only other vetoplayer, X can choose X1
If also B is a vetoplayer, then X will choose X2,
That cannot be closer to X than X1.
The advantage from having agenda setting power decreases with more veto players
The decisional rules in force in each collective veto player affects the final outcome
CThe core and the winset when there is the unanimity rule
A, B, C are member of a collective veto player and SQ is the status quo
This is the unanimity core
This is the winset in the same circumstance
If the collective veto player adopts the unanimity rule then it happens what we have already seen with 3 individual veto players
From the unanimity to the majority the winset expands..
..and the core becomes empty. It does not exist any point that belongs to all Pareto sets of all majority coalitions
Therefore when the veto player decides by using the majority rule is easier to agree to change the status quo
SQWincircle dello status quo
When SQ is in the hatched area, change is not possible with individual VPs. It may be possible with collective VPs, but it will be incremental
However there are some very important differences: