In recent years, with the EU institutions appearing to be led more by head than heart, many people have begun to question the wisdom of the project.
The fundamental importance of union has slipped out of view.
There are people in this Chamber whose parents lived through not just one great war, but two.
When I was growing up, Franco was still ruling with an iron fist in Spain, and Salazar in Portugal.
The EU has been an essential force not just in building peace, but spreading democracy.
Similarly, it has been an essential force not just in promoting prosperity, but equality and human rights.
It was the EU which put equal pay on the agenda, the EU which prioritised the rights of people with disabilities.
When the EU was at its highest standing, countries were queuing up to join.
Now, sadly, we are looking at a situation where one member state is considering the option of leaving.
I believe that would be a terrible mistake that would have consequences not just for the UK, but for Ireland and the EU as a whole.
This is a year that underscores the degree to which Ireland and the UK are intertwined.
On one hand, we are commemorating 1916, and the Rising that sparked the flame of independence from empire.
On the other, we acknowledge that, over the last 25 years, as we gradually worked towards peace in the North, relations between Ireland and the UK are closer than they have ever been.
So when we broach the issue of Brexit, we don’t do so in an attempt to interfere in the decision of a sovereign state.
We do so because our economies and societies and the fates of our people are intertwined, and the UK’s decision will have implications for Ireland.
This is why I suggested we hold this debate today as a matter of priority, because the referendum is drawing nearer and we must be ready come what may.
In nine weeks’ time – little more than the short period in which we have been teasing out government formation – the people of the UK will go to the polls on this vital issue.
The Government’s position is clear, and has been for some time.
We want the UK, as our friend, closest neighbour and partner, to remain a member of a reformed EU.
The word “reformed” is important in this context.
As a social democrat, as someone who believes that the single best protection against poverty is secure and fairly paid work, I was appalled by the EU’s initial response to the financial crisis.
Too slow, dictated from the centre, and ideologically blinkered in approach.
As a Minister from 2011, I argued repeatedly that the EU needed to shift from austerity towards a policy based on investment, growth and job creation – with full employment the central target.
I pressed the case for that shift at European level at every opportunity, something I continued to do when I became Tanaiste and Labour Party leader.
And thankfully, the EU’s approach did change, even if the pace of change was frustratingly slow.
From the EU-wide Youth Guarantee to help young people find work, training and education, to the ECB’s attempts to boost member state economies, the EU finally got onto the right track.
I mention this because it’s perfectly legitimate for European citizens to have questions, to have doubts, about the EU.
But I still fundamentally believe that all member states – including Ireland, including the UK – are stronger within.
And the task we face is to restore the great solidarity that underpinned the European ideal, because that solidarity will be essential if we are to tackle today’s global challenges.
We’re stronger working together than going our separate ways – because there are so many problems we are better facing together rather than alone.
The migration crisis is the latest, tragic demonstration of that.
The same can be said for terrorism, with the horrors of the attacks in Belgium and France to the forefront of our minds – no single member state can combat that spectre alone.
Energy security, climate change, and a world economy that recognises no borders are just some of others.
So we want the UK to remain because, as a general principle, we are stronger working together in a globalised world.
But there are also three specific reasons why we want the UK to stay.
The first is the economy.
More than €1bn of goods and services are traded every week between the UK and Ireland.
Anything that might get in the way of seamless flows of goods, services, capital and people between our two countries is not welcome.
The second is Northern Ireland.
The EU has been an important factor in sustaining peace and prosperity in Northern Ireland.
Much-needed funding, including through programmes like PEACE and INTERREG, will provide almost €3bn in the six years to 2020.
North-South cooperation is much easier when both jurisdictions are members of the same Union.
The third relates to the EU institutions themselves.
The UK is an important, influential voice at the table in Brussels.
We are allies on many of the key issues facing the EU.
The withdrawal of the UK would weaken the Union both in substance and reputation at a time of serious challenges.
Should the UK vote to leave, we would enter uncharted waters, a period of instability that could be enormously damaging to Ireland at a time when we have just got back on our feet.
That is why it is crucially important that there is a clear understanding of the issues.
Irrespective of the outcome of the UK referendum, Ireland, as a competitive, diversified and global economy, will remain a committed member state of the EU and a full member of the Eurozone.
As a small open economy, we value our access to a single market of over 500 million people.
But we also recognise that the project has been tarnished and lost traction in recent decades, and that we must tackle this problem.
The European model worked extremely well for much of the first 50 years, when member states developed a rough consensus about how to tackle economic and societal issues.
Many of the solutions put in place were those advocated by the centre-left – the welfare state, public health services, workers’ rights, women’s emancipation and social dialogue.
There truly was a social Europe.
In recent years, leading up to and after the financial crisis, policy shifted right, the consensus weakened, progress stalled, and we haven’t faced today’s great challenges with the vigour – or sense of fairness - that Europe tackled them in the past.
The only way to do that is by working together to restore the social Europe – to the benefit of all our people.
As Jean Monnet said, “beyond (people’s) differences and geographical boundaries, there lies a common interest”.