You don't have to believe Corbyn is antisemitic to see that the Chief Rabbi's attack on him is harmful
There is both a moral and a practical dimension to Labour's desperate slowness to root out antisemitism.
The moral one, highlighted by the Chief Rabbi last night, is whether Jeremy Corbyn is fit to be prime minister having seemingly been too tolerant for too long of avowed antisemites.
The practical one is that Labour is offering the most ambitious and complex programme of national reconstruction since 1945 - an expansion of the apparatus of the state on a scale we haven't seen since at least the 1960s and probably not since 1945.
It will require management and technocratic expertise of a very high order.
Chief Rabbi warns ‘soul of nation is at stake’ if Labour wins General Election
Former Labour MPs back Chief Rabbi’s condemnation of Jeremy Corbyn
Louise Ellman quits as Labour MP saying Jeremy Corbyn ‘is not fit to serve’
And yet Labour's administrative machine failed miserably to respond in a timely fashion to a practical challenge that was of a considerably lesser order, namely the multiple disclosures that antisemitism was poisoning the party.
This failure over years led in the end to the Equalities and Human Rights Commission launching an investigation into whether Labour is institutionally antisemitic - a humiliation for a mainstream party that is hard to match.
This failure by Labour was of bureaucracy as much as ethics.
It augurs ill for a party that would embark on four enormous nationalisation programmes, the creation of a giant National Investment Bank, the wholesale greening of the economy, the construction of a brand new state owned pharmaceutical and electric battery companies, the largest programme of council-house building since the 1960s, the wholesale remaking of the relationship between unions and business, and a revolution in the ownership and governance of private-sector businesses.
The point I am making is not in any sense a political one. I am not saying there aren't powerful economic or social-justice arguments for all or any of these plans.
In fact I bring to your attention a letter in this morning's Financial Times from 163 academic economists, led by the former member of the Bank of England's monetary policy committee, Danny Blanchflower, arguing that Labour properly understands the deep flaws in the UK economy and therefore deserves to be elected.
But the economic case for Labour is one thing (and you either buy into it or you don't). The competence case is entirely different.
The reason the Chief Rabbi's intervention is significant is that it poses uncomfortable questions for Corbyn and his top team not just about their values but about their skills in driving through important change, let alone manage in a crisis.