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What is the optimal number of TDs for Ireland? There’s a formula for that

Michael Gallagher: Agreeing to a fixed-sized Dáil, no more three-seaters and stable constituency boundaries would deprive political anoraks of some excitement but it would be better for democracy

The publication last week of the report of the Electoral Commission – and kudos to the commission for being so willing to engage with the media and other interested parties – has been described as Leaving Cert results day for political anoraks, and its implications have duly received much expert analysis, in this paper and elsewhere.

Fascinating as it is to figure out the implications of the redrawing of constituency boundaries, something that now happens more or less every five years, the question arises: should this be happening at all? There are three aspects of the process that make Ireland a real outlier in a European context when it comes to constituency formation.

First, the number of seats per constituency (known by the term ‘district magnitude’) is exceptionally small for a proportional representation (PR) system. With 174 seats and 43 constituencies in the next Dáil, average district magnitude is barely above four, much lower than that of most European countries that employ PR. In Spain, for example, it’s seven, while in Finland it’s more than 15. Analyses of how electoral systems operate concur that an average district magnitude of at least five is needed if the system is really to deliver proportional outcomes.

In particular, three-seat constituencies are simply too small to ensure proportionality. Smaller parties are disadvantaged by this, but the primary concern is not about being “fair” to parties; rather, it’s about being fair to voters and ensuring that the composition of the Dáil reflects the way people voted. The commission had no option but to abide by the legislation that specified that it was confined to proposing constituencies in the three to five range, but one can only hope that this is the last time we hear of three-seaters. A mix of constituencies in the range of four to six, or four to seven, would guarantee an average district magnitude of about five.


Three-seater constituencies are simply too small to ensure proportionality

Second, it’s very unusual in a comparative context for the size of parliament to fluctuate constantly. The Dáil had 166 seats in 2011; 158 in 2016; 160 in 2020 and will have 174 at the next election, and is set for more again at the following election. The norm across the world is for the size of parliament to remain fixed over time, with changes occurring only rarely. Finland has had exactly 200 MPs for over a century; Austria 183 for over half a century; Denmark 175 for 70 years; Sweden 349 since the mid-1970s; and so on.

Incidentally, whenever the size of the Dáil is under discussion, we invariably hear the hackneyed refrain that since the UK has a parliament of 650 MPs for a population of nearly 70 million, surely Ireland has far too many TDs per capita. (This concern is sometimes fuelled by a vastly exaggerated notion as to the cost of running the Oireachtas.) Indeed, if we took the ratio of population to MPs in India as the norm, the Dáil should consist of only two TDs. Alternatively, if we were to use Malta as the touchstone, the Dáil would need to be expanded to more than 800 TDs.

Drawing facile comparisons with much larger or much smaller countries misses the point, because we wouldn’t expect parliament size to be related in a linear fashion to population size; that is, a country that has 10 times the population of another probably doesn’t need 10 times as many MPs. (Unfortunately, the assumption that it does is inherent in Article 16.2 of the Constitution.)

Many years ago Estonian political scientist Rein Taagepera, having examined parliament size around the world, came up with the ‘cube root rule’; that is, if we cube the size of parliament we should arrive at a number pretty close to the size of the population. The next Dáil will have 174 members, and 174 cubed equals 5.27 million; not much above the 2022 census population figure, implying that 174 is a very appropriate size for the Dáil.

Applying this logic to Ireland would suggest that fixing the size of the Dáil at, say, 180 TDs would ensure a parliament size that would be acceptably close to the requirements of the cube root rule for several decades into the future.

Third, the very idea of constantly redrawing constituency boundaries is very unusual in a comparative context; it’s been described by UCD political scientist John Coakley as an “eccentric” approach. The more common approach, used throughout Europe, is that constituencies, defined usually by county boundaries or equivalent, remain fixed over time, and all that changes, in response to population changes, is the number of seats that each receives.

Thus in Ireland, the entire county of Wexford would constitute one constituency in perpetuity, as would Wicklow, while larger counties such as Cork would be divided into several constituencies (again with unchanging boundaries) and smaller ones could be combined (Coakley suggests a Connacht East constituency comprising Leitrim, Roscommon and Sligo returning 6 TDs, for example).

Each of these 35 or so constituencies would receive a number of seats determined simply by their population, as occurs elsewhere in the EU. Thus Wicklow, for example, might be entitled to five of the 180 seats; if its share of the national population were to grow this entitlement might increase to six or seven, and if it grew larger still it would be divided into two four-seaters.

The ideas of a fixed-sized Dáil and stable constituency boundaries would both require constitutional amendment, but this is nearly inevitable anyway unless we wish to see the size of the Dáil continue to grow in lockstep with population growth far beyond the requirements of the cube root rule. With such changes, political anoraks would be deprived of some excitement, but that would be a price well worth paying.

Michael Gallagher is an emeritus professor at Trinity College Dublin and co-editor of the recently-published Politics in the Republic of Ireland (7th edition).