What can parliamentary politics achieve? Not much, says Paul Mason:

Elected politicians have little power; Wall Street and a network of hedge funds, billionaires and media owners have the real power, and the art of being in politics is to recognise this as a fact of life and achieve what you can without disrupting the system.

On the other hand, though, Danny Finkelstein attacked John McDonnell yesterday for being "contemptuous" of the idea that we can achieve socialism through parliament alone.

Here, I side mostly with Mason and McDonnell against Finkelstein. In many of the main social changes of my lifetime, parliament has played a relatively minor role. For example:

- Brexit. Most MPs wanted us to remain in the EU. We got out because Cameron called the referendum in part because of pressure from Ukip, and Leave won because of the work of people who weren't MPs. If you want an example of effective extra-parliamentary political action, you should look at Farage more than any leftist.

- Gay rights. Isle of Wight MP Andrew Turner recently resigned after making homophobic remarks. When I was a young man, however, an election campaign was based successfully upon homophobia. This huge change, from gays being stigmatized and homophobes accepted, to the exact opposite was achieved mostly without parliamentary intervention but by changes in social attitudes. Yes parliament legalized homosexuality in 1967, but that alone did not remove anti-gay sentiment.

- The decline in crime. This is unlikely to be mainly due to government policy, simply because (pdf) crime has dropped in many countries with different policies. Instead, socio-technical changes are more responsible. Stuff is harder to steal, and young people play computer games rather than hang around on street corners.

- Greater gender equality. As Jeremy Greenwood has shown, this is due more to technical change than legislation. The greater availability of contraception not only gave women control over their fertility but also helped destigmatize pre-marital sex. And household technologies freed women up to enter the labour force.

Now, I'm not saying that parliament is irrelevant. It did play some role in the changes I've mentioned. The Equal Pay Act helped increase gender equality, for example, and the repeal of section 28 helped destigmatize homosexuality. Both, however, followed extra-parliamentary campaigns. And of course, increased inequality since the 1970s is due at least in part to parliamentary politics such as anti-union legislation and lower top tax rates. Remember, though, that those policies were themselves the product of extra-parliamentary action by right-wing think-tanks aimed at changing ideology.

Nor do I want to side wholly with Mason against Finkelstein. I fear that in attributing power to hedge funds and media bosses, Paul under-rates the importance of emergence and endogenous ideology. And I agree with Danny that placard-waving is often ineffective and that permanent revolution is "preposterous."

Nevertheless, the evidence suggests that parliamentary politics alone does not bring lasting social change. It might be necessary for such change - we'll not get a citizens basic income without it but this too requires an extra-parliamentary campaign first - but it's not sufficient. A stronger parliamentary Labour party is much to be desired. But this alone is not enough to achieve the sort of changes we on the left want.