What goes on inside Harriet Harman's head?

I was in Westminster today and looked in at the Commons Press Gallery. There was an Opposition debate on "Electoral integrity and democratic accountability", and it was of a surprisingly high quality. I may write about it when I have the Hansard transcript in front of me.

There is one thing that probably won't appear in Hansard, though. It was something of a surprise to see Harriet Harman on the Government front bench. In fact it was something of a surprise to learn she was still alive, so dark is the eclipse of her career these days. She was once rated extraordinarily highly by the Guardian-reading classes.

Anyway, Harman is a good-natured woman and happy to engage in chat and banter across the floor of the House. When Clive Betts suggested that one way to ensure the electoral register is accurate would be to link it with the national identity database there were groans from the other side. At which she brightly suggested: "That's the best argument in favour of a national identity card."

In case you have forgotten, Harman was legal officer for the National Council for Civil Liberties (the organisation now called Liberty) between 1978 and 1982.

I often wonder how people who change their beliefs so fundamentally justify it to themselves. What goes on inside their heads? Don't we all try to construct a narrative that makes are decisions principled and consistent?

Maybe Harman now regards her NCCL years as a bit of youthful nonsense. Or maybe she tells herself that the she hasn't changed but the world around her has. I have never heard her - or Patricia Hewitt, for that matter - offer an explanation of their conversion to authoritarian government.

We condemn someone like Eric Hobsbawm for not giving up his Communism after the Soviet tanks went into Hungary in 1956. Yet this refusal to change your views when developments show you are wrong seems more understandable, more human, than changing them fundamentally and then pretending that nothing has happened.