Ok so here are my thoughts on the subject, I encourage people to give me feedback and their own opinions on this subject.
Events and policies that could encourage federalisation:
In my opinion this is one of the most important factors in achieving a lasting federation. A common European identity would allow national governments to justify handing greater powers to a federal government. This could be achieved by adopting an EU wide policy of teaching European history in schools. This would give European citizens a sense of being part of a greater European community rather than just their respective nations. As well as this, i believe a first language needs to be adopted and taught across all schools to further help co-operation and integration. Preferably this language would be English as it is already the dominant language in the western world. However, as I am British I feel my stance on this is somewhat bias. I am sure that the French would never agree to such a proposal.
An external threat that is beyond the control of a single or group of national governments. such as for example, a resurgent Russia. I choose Russia as the example because if it did become hostile towards the EU it is not just limited to conventional warfare but can destabilise governments using a number of methods. (Please keep in mind these are purely hypothetical, i am in no way insinuating Russia will do these things.) This includes cutting off the energy supply to many European countries, cyber attacks on critical infrastructure, subversion and even sponsored terrorism. Politicians could use these events to justify accelerating federalisation and urge greater co-operation and unity in order to overcome their effects. This being said, unity against an external threat usually only lasts as long as the threat exists, once gone i believe the need for unity would be diminished.
Currently this is probably the most unlikely situation i have posited but, if the United States did become reclusive and inward facing due to internal problems its place as the worlds dominant power would be greatly diminished. This in my opinion would lead to calls by many governments to foster stronger regional security. Without the protection of the United States, Europe would have to take full responsibility for the stability of the region. This could be achieved without federalisation but would not have as great effect due to the larger resources able to be mobilized as well as a more efficient and comprehensive implementation an EU wide response could achieve. This includes the massive military R&D and space programs the US undertakes as well as the somewhat effective military deterrent NATO currently provides.
The benefits provided from a federalised Europe
A federal Europe would build upon the success of the EU and its predecessors in taming the nationalism that caused so much conflict in the twentieth century by providing a comprehensive diplomatic framework in order to solve differences and disputes. The EU is drawing nearer to realising the vision of its founders for an “ever-closer union”. Despite the EU’s relative success in this regard, while national governments still exist they will regard policy-making within Europe as a competitive business, abusing vetoes and damaging the potential prosperity of all of Europe’s citizens. Such is the case with Britain's veto over the carbon tax, which the EU wants to implement - “The British government is "highly likely" to block European Commission proposals for a carbon tax contained in a widely-circulated draft version of the Energy Taxation Directive, EU diplomatic sources said yesterday”. A federal European state can build on the shared history and culture of its members to further the common good, while accommodating regional differences. I advocate the implementation of a rather decentralised federal government which would still allow national governments (though they could be replaced by uniform regional/national assemblies rather than each having their own unique political systems). This would allow the people of each region/nation to implement culturally/regionally specific policies.
*A federal Europe will be better equipped to promote the interests of its citizens in the world, carrying more influence in the UN, WTO, IMF and other intergovernmental and treaty organisations than its individual states do now. Furthermore, Europe has a lot to contribute to the world in terms of its liberal traditions and political culture, providing both a partner and a necessary balance to the USA in global affairs.
Once unified, Europe will become an (even more) important negotiating and trading partner – one of the biggest economies in the world. It will have a population of 450 million – more than the United States and Russia combined. It will be the world’s biggest trader and generate one quarter of global wealth. It presently gives more aid to poor countries than any other donor. Its currency, the euro, comes second only to the US dollar in international financial markets. France, Germany, Poland - these countries can hardly ever negotiate something with giants such as the US or China. Europe as one country stands a better chance of putting its message across effectively.*
In a globalised economy, there is a need to tame multinational corporations, which would be otherwise capable of playing national governments off against each other in search for low wages, social costs and state protection. A federal Europe would be powerful enough to demand high standards of behavior from such companies, because only a powerful and economically significant player can dictate restricting conditions. This would ensure fair wages, safe working conditions and - additionally - Europe would be able to force multinational companies to implement correct and holistic policies and would also be in a position to make a greater difference on environmental issues such as global warming. Sovereignty becomes less relevant when effective independence is lost anyway as the economy and the problems faced by all nations are increasingly globalised.
I will add more points tomorrow if I remember.