1 Introduction, Parties and Aggregation

Democracy is by nature a form of aggregative choice. Means have to be found of combining the votes of the people or their representatives and those means must themselves conform to democratic standards.

There are at least four profound difficulties in meeting such a challenge. The first relates to the political equality conditions for democracy (Beetham 1994 : 28; Weale 1999 : 14). Whereas the simple rule ‘one person, one vote’ makes it easy to proceduralise political equality at the level of the individual citizen, matters become more difficult when it comes to combining votes. It is difficult to think of any method of aggregation that does not make the votes of a few pivotal to decisions binding on all. Maybe at best we can only design systems so that the pivotal few are likely to be representative of the rest. Thus, systems that encourage competition for the support of the median decider have the advantage (where preferences are one dimensional and normally distributed) of handing the pivotal role to the actor whose views are the least average distance from all the rest (Powell 1989 ).

A second well-known difficulty in the study of aggregation is one of avoiding non-arbitrariness. Ever since Kenneth Arrow’s ‘impossibility theorem’ (Arrow 1951 ), social choice theory has been aware of the difficulty of designing any system for aggregating preferences – representative institutions included – that simultaneously satisfies what Armatya Sen describes as the following ‘mild-looking conditions’: a) pareto efficiency; b) avoidance of interpersonal comparisons in which some preferences are assumed to be better than others; c) independence of preferences and d) complete and consistent rankings of preferences (Sen 2002 : 72).

Under further conditions – notably where preferences cannot be arranged along a single dimension of choice – matters become so indeterminate that an infinite number of outcomes are possible. Any ideal of procedural neutrality in which it is only the choices of citizens and their representatives that matter, and not the means of combining them, collapses all too easily into its opposite: the method of aggregation becomes the key determinant of what is decided (McKelvey 1976 ). Hopes that procedures can be chosen from behind a ‘veil of ignorance’ as to who will benefit from them (Rawls 1993 ) have to contend with structural incentives to manipulate procedures to achieve specific outcomes (Riker 1982 : 305).

A third challenge follows from John Dewey’s famous observation that voting can never be enough in a democracy (Dewey 1927 : 207). Since voting is in many ways a remarkably coercive form of choice (see also Dunn 2005 : 19 on how democratic governments ‘add insult to injury’ by closing ‘the circle of civic subjection’ in ‘their citizens’ own name’), it is unlikely to be acceptable without arrangements that demonstrate to the outvoted that their preferences have been set aside ‘for reasons’ and not through mere ‘acts of will’ (Mill 1861 : 239-240). Any system of aggregation, in other words, needs to be accompanied by one of deliberation and justification (on this see also Habermas 1996 ).

A fourth challenge is motivational and cognitive. If my vote is most unlikely to be one that makes a difference after it has been aggregated with everyone else’s (Downs 1957 ) what can motivate me to take part? How, indeed, can I know how to combine my vote with those of millions of unknown others so that all of our behaviours have some chance of producing their intended effects?

How democracies respond to these problems of aggregation is partly a matter of institutional design, and partly a matter of how actors organise themselves in relation to the political system. Political parties are foremost amongst those actors who can help or hinder. They can help by:

Competing around broad approaches to government parties in ways that allow all issues to be considered in relation to all others. This is likely to be especially useful where externalities and cumulative unintended consequences dictate that choices of value cannot optimally be made issue-by-issue.
Directly or indirectly offering the same menu of choice across the political system, so that any two voters can co-ordinate their actions by simply voting for the same party programmes on offer, even though, of course, most voters are unknown to one another (Cox 1997 : 5).
Simplifying choices so that citizens can participate in complex democratic systems with only minimal information. Meaningful choice may require no more than an understanding of the ordinal (i.e. relative) position of parties along a key dimension of choice, such as left-right; or no more than an opportunity to renew or recall existing patterns of power-holding by voting for parties of government or opposition.
Solving some of the inter-temporal problems of democratic politics. Individual power holders may come and go, but in systems of ‘party responsible government’, parties can be held responsible for governing performance. They can also have a developmental role where use of a political system by voters and their representative to achieve output or input democracy is a capability that grows with use (March and Olsen 1995 ). Parties recruit and train elites in specific forms of expertise needed for representation. With time, voters may also have a clearer idea of what it is to choose between parties.

Yet, there is no guarantee that parties will perform these roles very well in practice. Rather than compete for the favours of the voters, they may carve up the benefits of a political system between themselves (Katz and Mair 1995 ; Blyth and Katz 2005 ). They may fail to form even where there is an identifiable group capable of being represented (Olson 1965 ); or they may fail to supply choices in relation to a particular level of government.

So what of the European Union: do parties contribute to aggregation in ways that help or hinder its democratic performance? Do we even know enough to answer this question in full? After introducing the dramatis personae (Section 2) this Living Review appraises what we know about the contribution of party politics to the aggregation of preferences amongst representatives (Section 3), voters (Section 4) and the two combined (Section 5). Section 6 discusses what more we need to find out and Section 7 concludes. There will necessarily be limits to how much of the literature that can be covered here. In particular, the author has concentrated mainly on English and French language sources. Since, though, this is a ‘Living Review’ it is hoped that readers will treat the whole exercise as open-ended and come back to the author with their own comments on what further arguments and sources need to be incorporated into a summary of recent research into political parties and the EU.