Jonathan Bartley: I know from painful experience the pitfalls of tribal thinking

"There is nothing new of substance from John Redwood today" ran the first line of the internal briefing. That would have been fine, except that the document, "Lines to Take" was issued first thing in the morning – long before John Major's opponent in the leadership election had a chance to say much about anything. I wasn't really a Tory and fell into the PM's campaign team more by good luck than good management.

Only a year before, I had entered the House of Commons as a lowly researcher. Any idealism had been knocked out of me on my first trip to the Whips office. I was sent to pick up a brief for an upcoming debate. Naively I had expected balanced information. What I found instead were carefully crafted statistics and facts, designed to talk up our position and tear down those of our enemies. The system operated with different values to the pursuit of enlightenment prized at my university.

There may always be the need for a system involving some alliances and groupings. But tribal thinking aims at power, not truth. It has always been the case. In the biblical account, standing before Pilate at his trial, Jesus makes the bold claim "everyone on the side of truth listens to me". The politician's question was to ask "What is truth?"

Even then there were lies, damn lies and statistics – but the Galilean's statement went to the heart of the issue. Truth isn't just propositional. It is relational. And the system works against this too. There is a route to becoming a MP. Join the party. Get listed as a candidate. Fight your "no hopers". Find a safe seat. Constituents are, first and foremost, a means to an end.

The more partisan the politics, the greater the human cost. Migrants and asylum seekers, the unemployed and the disabled become political footballs. Creative policy solutions such as restorative rather than punitive approaches to criminal justice are sidelined – even though they might help both victims and offenders. Any party would become too vulnerable if it championed them.

Truth does have a price. In the historical example it was the Jew who footed the bill. But if he is to be believed, we shouldn't let politicians get away without settling their account either.

Jonathan Bartley is co-director of Ekklesia, a think tank. www.ekklesia.co.uk