Why is the Scottish Labour leadership so abysmal? Why has it struggled to adapt to post-devolution Scottish politics, and why does it keep having rings run around it by the SNP?

For example, by any reasonable definition, Johann Lamont's policy announcement on Tuesday was a train wreck. After Iain Gray's lacklustre, gaffe-prone and election-losing leadership, pro-Labour pundits had persuaded themselves that Lamont was quite a heavyweight Scottish Labour leader. They should be face-palming. The policy implications of Lamont's speech – ending universal benefits, raising tuition fees, cutting free prescriptions – were bad enough. The atrocious, reactionary soundbites, demanding an end to "something for nothing" culture, were worse. And it was all delivered in a colliding procession of clichés and non-sequiturs, with faltering speech, and without conviction.

Lamont's follow-up interview with STV reporter Bernard Ponsonby went no better. She fluffed her lines, struggling to remember that it was NHS computer systems that were wasteful and an obvious area for cuts: naturally enough, since it is an entirely forgettable argument. Ponsonby was admiring enough to call Lamont's speech "brave" and "almost Blairite in substance". It is certainly Blairite; but if it is brave, then so are lemmings. Outside Scotland, this policy would merely be a gift to the Tories, by corroborating their arguments for welfare cuts. In Scotland, it reminds ex-Labour voters why they defected to the SNP: as a defensive shield against such policies.

There may be some pragmatic realpolitik at work in this policy. Lamont is the latest in a sequence of weak Scottish Labour leaders, who needs the backing of her party. She cannot outflank the SNP to the left on public services and welfare. Though the SNP's policies, such as no tuition fees, and free prescriptions, are extremely moderate, they press to the limits of the neoliberal constraints accepted by all the main parties. Labour, unwilling to break these constraints, attacks the SNP on priorities. Lamont's tactic, therefore, is to imply that SNP freebies are benefits for the rich, and that they are frivolous in an age of austerity, as they deprive local government, hospitals or higher education of necessary funding.

A cuts agenda vaguely articulated in the language of class resentment and protecting "frontline services" would satisfy Balls and Miliband, and play well with cash-strapped local Labour councils, thus uniting powerful sections of the party behind Lamont's leadership. But it clearly wasn't thought through even on this cynical level. You cannot stutteringly vaunt "tough choices" one minute, and weakly refer to cutting wasteful referendum spending the next. It gives the impression of being all mouth and trousers.

Part of Labour's problem is that it is blinded by hostility to the SNP. In practical policy terms, it has few real differences with the SNP, with the major exception of independence. And even there, a tacit convergence around "devo max", devolving all powers to Scotland barring foreign and defence policy, is very plausible. Labour's hatred is so toxic because of the threat that the SNP represents to their monopolistic control of working-class heartlands. Whereas the SNP tactfully preserved some of the reforms made by the Labour-Liberal coalition, Labour consistently shoots itself in the foot by adopting the most hardline anti-SNP postures. Its lapse into belligerent, uncompromising Unionism is a case in point.

Scottish Labour's unionism is another part of the explanation. The party doesn't just believe in the union for pragmatic reasons to do with preserving its electoral future. A post-British Labour party is a regional party in a much-diminished capitalist power. Labour's whole strategy for implementing any form of social democracy depends on the unity and power of the British state, its international competitiveness, its permanent membership of the UN security council, its role in Nato, and so on. That is how they expect to deliver the growth to pay for public services, however emaciated. Scottish Labour thus cannot embrace a growth formula for Scotland that is markedly different from, or detached from, that operating in Westminster. Unless it accepts the logic of independence, it must try to bring Holyrood policy into line with London. Ironically, the straitjacket imposed by unionism in its neoliberal phase is one of the factors boosting popular support for independence.

Scottish Labour is thus caught in a vicious circle. The more it suffers electorally, the more it loses whatever political talent it has accumulated. It moves from disaster to disaster, from Alexander to Gray to Lamont. The more the SNP demolishes it, the more bitterly hostile Scottish Labour becomes, and the less rationally it responds to its crisis. The more it loses its working-class base and becomes dependent on an active middle-class membership, the more the Blairites gain control, and the less it seems interested in regaining its lost base. The point at which the vicious circle becomes a death spiral, however, has just moved much closer.