Erik Moberg ã:

A Theory of Democratic Politics

11.2 - THE IMPOSSIBILITY OF A COALITION WITH A PURELY IDEOLOGICAL FOUNDATION

In part 11 I said that a coalition executive cannot have
a purely ideological foundation. This, in fact, is a theorem which says
that it is impossible to account for the formation of the executive only
in terms of a simple a left-right scale, or, in somewhat more technical
terms, that *it is impossible to account for the formation of the executive
within the framework of the spatial model*, at least in its one-dimensional
version. (For an account for the theoretical context of the theorem see
Moberg, 2000.)

In the figure below we see a situation which can be used
for proving the theorem. The figure represents a legislature with six political
parties, *P** _{1}*-

For proving the theorem we may compare this situation
with one in which there is an executive. Clearly, if the executive is to
make any difference at all, and thus to be of any interest for its members,
its policy must diverge somewhat from *m*. We may for example think
about an executive which has the policy indicated by *l*, and thus
a leftist inclination, and which is supported by the majority composed
of *P** _{2}* and

Now, it is easy to see that *l* is worse than *m*
for *P** _{3}*.

So far I have only dealt with the particular example in
the particular figure above. Obviously we have to ask if other examples,
with other possible party constellations in the legislature, also lead
to contradictions for the same reasons. The answer is in the affirmative
since the examples, however they are varied, will always have two crucial
properties. First, the executive's policy must always diverge from *m*
since otherwise the executive would not matter at all and, consequently,
it would not be important to be a member of it. Second, since the constellation
supporting the executive has to be a majority, it necessarily includes
the median member of the assembly. (This, of course, presupposes
that the coalition supporting the executive is connected, but departing
from this assumption does hardly add anything of interest.) Thus, contrary
to our assumptions, the executive will always include at least one party
member for whom the membership is a unfavorable. We are thus entitled to
draw the general conclusion that it is impossible to account for the formation
of the executive within the framework of a simple, one-dimensional ideological
model.

As a contrast, as mentioned in part 11, it is easy to account for a coalition executive in terms of interests. Thus, the parties belonging to an executive can, for instance, agree to tax those outside the coaltion and share the spoils between themselves.