The Scottish National party will campaign confidently for independence, not just as an end in itself but as the means by which the people of Scotland can best fulfil their potential and realise their aspirations; by which the Scottish economy can grow more strongly and sustainably; and by which Scotland can take its rightful place as a responsible member of the world community.

When I was in Liverpool last year for an appearance on BBC Question Time, I received an enthusiastic response. Perhaps the strongest support I got was when I made a plea to the audience not to let the three biggest Westminster parties destroy England's National Health Service – just one of many issues where the Westminster class are out of touch with the people of England.

Looking at the chaos of health reform in England now, I thank the heavens that Westminster's writ no longer runs in Scotland on health issues. But the looming issues of welfare reform exemplify why Scotland needs the powers to make our own policies to meet our own needs and values.

For instance, we have promoted what we call a "social wage" for our citizens. We have made a conscious decision to provide certain core universal services, rights and benefits, some of which are no longer prioritised by political leaders elsewhere in the UK – such as free university tuition, no prescription charges, and free personal care for the elderly.

We do this because we believe such services benefit the common weal. They provide a sense of security, wellbeing and equity within communities. Such a sense of security is vital to a sense of confidence – and as we have seen over the last three years, confidence is essential to economic growth.

We will provide a secure, stable and inclusive society. And by doing so we will encourage talent and ambition. Scotland will be a place people want to visit, invest, work and live in. Doing this has required some difficult decisions – such as major efficiency savings and a freeze in public sector pay. But those are easier to implement if your policies clearly have fairness at their heart.

The concept of a social wage exemplifies one reason why people in Scotland want additional powers for their parliament: they largely like what we have done with the powers we already have.

There are many examples of how the ability of Scotland to make independent decisions has had a beneficial effect on wider policy debates. An obvious one is the introduction of a smoking ban before the rest of the UK. And we have championed minimum pricing for alcohol – a policy that is attracting substantial interest south of the border and elsewhere.

This innovation benefits Scotland – which can respond to specific Scottish problems and circumstances. But it also benefits the rest of the UK, and potentially the wider world, by providing a working precedent for policies other countries can then either adopt or not.

An independent Scotland can be a beacon for progressive opinion south of the border and further afield, addressing policy challenges in ways that reflect the universal values of fairness and are capable of being considered, adapted and implemented according to the circumstances and wishes within the other jurisdictions of these islands and beyond.

That, I believe, is a far more positive and practical Scottish contribution to progressive policy than sending a tribute of Labour MPs to Westminster to have the occasional turn at the Westminster tiller – particularly in the circumstances ofas the opposition's policy increasingly converging with that of the coalition on the key issues of the economy and public spending.

The problem with Scotland's current constitutional settlement is that we cannot innovate as much as we would like. Policy choices made in Westminster – by parties whose democratic mandate in Scotland is negligible – are constraining the policy choices made in Scotland, for which there is an unequivocal mandate.

The shift from administrative to legislative devolution was, of course, momentous in itself. But it still left Scotland with fewer powers than the German Länder, most American states, parts of Spain or, within these islands, the Isle of Man. The economy is where this is felt most deeply. What independence would do is to give us the tools – corporation tax, for instance, or alcohol excise duty – which we could use to get on with the job of promoting recovery and improving our people's lives.

Importantly, economic policy could be implemented in a co-ordinated way so that welfare, tax and enterprise policies would be in harmony with each other. And independence would allow Scotland – finally – to make the most use of its own energy resources.

Scotland as an independent nation would play an active and responsible role in the international community, contributing on issues where it could, but without delusions of grandeur. I find it inconceivable, for instance, that an independent Scotland would ever have participated in the invasion of Iraq.

Independence for Scotland would still leave us free to work together in the many areas where we do share common values and interests. The British Irish Council already provides a model of how all the people of these islands can work together on shared interests. Does anyone seriously believe the council would look massively different with three independent states rather than two?

But most of all, in addition to these institutional, cultural, economic and practical links, Scotland shares ties of family and friendship with our neighbours on these islands which never can be obsolete and which will continue and flourish after Scottish independence.

And when you consider our shared economic interests, our cultural ties, our many friendships and family relationships, one thing becomes clear. After Scotland becomes independent we will share more than a monarchy and a currency. We will share a social union. It just won't be the same as a restrictive state which no longer serves the interests of either Scotland or England.

• This is an edited extract of the Hugo Young lecture Alex Salmond is delivering on Tuesday 24 January