The Treaty of Nice is primarily about the enlargement of the European Union. Twelve countries - 10 in Central and Eastern Europe, Malta and Cyprus - are at an advanced stage of negotiation and preparation for entry into the EU. The provisions of the treaty are designed principally to make the necessary changes in the EU's institutions - the European Commission, the Council of Ministers, the European Parliament, the Court of Justice, the Economic and Social Committee and the Committee of the Regions - to enable these countries to participate as full members.
If the treaty is ratified by all l5 EU member-states, enlargement can take place. If any one of the existing member-states fails to ratify it, enlargement cannot take place.
In Ireland, ratification requires a referendum. In the other member-states, ratification requires parliamentary assent.
Why enlarge the EU? There are many good reasons, from the points of view of both member-states and candidates.
The EEC succeeded in creating an area of peace, prosperity and stability among six states which, not long before that, had been at war. They subsequently welcomed Ireland, the UK and Denmark which had close trade and political ties with them.
When Spain and Portugal emerged from periods of dictatorship and Greece from a period of military rule, it was considered both politically and economically worthwhile to integrate those countries into the European Community to consolidate democracy and to boost the process of economic growth. Looking at those countries today, we can only conclude that the enterprise was successful on both counts.
Later, Austria, Finland and Sweden (which also had close economic and political ties with the EC 12) sought and secured full membership. On each occasion, the enlargement worked. The history of those enlargements shows clearly the benefits of closer economic and political integration.
Specifically, the cases of Ireland, Spain, Portugal and Greece show that the process works well for all, even where the applicants are at a considerably less advanced stage of economic development than the group they are joining. In every case, the economic effects of integration have been heavily positive for all the participants.
In the present case, there is a much larger gap than before between the levels of development in existing members and those in the candidate countries. On the other hand, the pressures to proceed rapidly with reforms are greater than ever in this era of globalisation.
The structural, economic policy and administrative changes which candidate countries must make to secure EU accession are, for the most part, changes they would have to make in any case to ensure the construction of successful, competitive, liberal market economies.
The further administrative, political and social changes they will have to make to conform to the non-economic parts of the "Copenhagen criteria" are also those required to ensure that systems of liberal parliamentary democracy under the rule of law are firmly embedded.
Providing support to the applicant 12 will cost member-states money. Membership will entitle them to participate in structural and cohesion funds and in agricultural supports. That will clearly require resources from the l5 in the same way that, in the past, "old" member-states supported "new" ones, with positive results all round. Self-interest and generosity in these matters are rarely in conflict.
The current candidate countries will, of course, compete with the l5 for foreign direct investment, a matter of particular importance to Ireland. That competition is bound to increase in any case, as they develop more and more effective domestic economic policies.
There is sense in the proposition that competition of that kind would produce a better result all round if it takes place within the context of a single, unified market embracing 27 countries.
It would produce better social results in the candidate countries if it took place in the framework of the EU social market economy model than if it happened in a laissez-faire framework, or in isolated economies where neo-communist tendencies can still be found.
It made sense for the original six to set up a zone of peace, stability and prosperity. It made sense to extend that to nine, then l0, 12 and l5. It makes sense from every point of view to extend it to 27. That is why we should vote Yes to Nice.