Apart from longer life expectancy, better health, improved education, a cleaner environment, better opportunities for our children and a happier country, what has economic growth ever done for New Zealanders?

Last night, MPs Chris Bishop, Dr David Clark and James Shaw debated the merits of economic growth, and of our recent report on it, at Mac’s Brew Bar in Wellington for an audience of about 150.

I opened by noting that every time a major regulation or spending programme or regulation is passed without a reasonable cost-benefit assessment, we’re effectively saying that economic growth does not really matter that much.

What’s a percentage point of difference? Consider the period since 1970. If real per-capita economic growth rates had been one percentage point higher, we would today have higher per-capita GDP than Australia and have the fourth highest income in the OECD, rather than sitting below the median. Australian economic growth only outpaced New Zealand’s by about a third of a percentage point over the period, but over 45 years, it adds up.

National’s Chris Bishop followed, eloquently reiterating the case for economic growth and dismissing some common critiques of growth. I especially appreciated his points on the recent worldwide diffusion of luxuries like the flush toilet. A friend in Christchurch, of about my age, remembers when his father installed their first flush toilet.

David Clark, for the Labour Party, also praised growth while noting the importance of measures to help workers to retrain where technological shifts proved disruptive. David made a thoughtful case too on the importance of culture in setting the preconditions for growth, emphasising the West’s Judeo-Christian heritage. It has seemed to me that the East Asian miracle of the last half-century points to the wide variety of cultures that can foster economic growth – when the political institutions allow it.

The Greens’ James Shaw argued that while developing countries’ environmental quality is likely to improve as they become richer, there are grave environmental disasters unfolding in many parts of the world that may be irreversible even with growth, like species’ extinction. But he also provided the most techno-optimist take on the world’s future, where economic growth has fully decoupled from carbon emissions and distributed manufacturing through 3-D printing brings us ever-closer to Star Trek replicators.

I really enjoyed the event. All three MPs provided very thoughtful takes on economic growth and the audience provided an excellent set of questions. There seems good consensus on the importance of economic growth, at least in principle. Now back to the harder task of building the evidence-base for policies that will take us there.