'Unity' has become the death of politics.
'Democratic centralism' - broadly, maximum democratic debate followed by binding unity of action - was imported into the broad cross-class social movements of the late 19th- and early 20th-centuries from the societies of socialist brotherhood operating underground before the liberalisation of labour laws. In its comparatively benign form, 'unity' as a concept underpinned the alliances between moderate labour unions and the bourgeois workers' parties; it permitted stable social-democratic social contracts - like the postwar consensus in the UK, or the New Deal in the US; albeit often explicitly to exclude more radical working-class factions.
These 'unified' movements were effective because they were able to extract redistributive concessions from ruling-classes: be it through the militancy of other contending groups forcing moderates to the table (cf. black civil rights in the US), the militancy of the movement itself (cf. the anti-apartheid struggle in South Africa), existential threats posed to the system (cf. the NHS in the context of the burgeoning Cold War). But in the 21st-century, progressives championing 'unity' require us to observe the circuses without the bread. The redistributive fruits of government - on the back of 40 years of institutionalised neoliberalism, an historically weak working-class movement only able sporadically to project its power, and with the hollowing of state mechanisms by systematic tax avoidance which has allowed the elite to opt out of any social obligation - no longer provide compelling reason to contend in common for limited reform.
In this context, the idea of 'unity' has degenerated. It has become for centrists a performative Shibboleth entailing lowest-common-denominator neoliberalism, justifying censorship of critics and minorities. It is wielded in service to demand compliance as an objective end in itself, rather than as a means of a movement welding over its diversities for the sake of common purpose.
We must take careful stock of those with whom unity is possible, and of those with whom unity requires the bending of our aims to such an extent that we no longer recognise them as ours. In concrete terms, that will mean the immediate reassessment of some of the deepest parts of the labour movement's history: for example, in the UK, the 120-year-old 'progressive' alliance between bourgeois intellectuals, the left-wing of capital and trade unions which underpins the Labour Party.
There is no quiet way to do this. Political realignment and the emergence of a new pole of working-class interests will be messy. But it is urgent, and must be carried out with concomitant urgency. To have the revolution, you must have the revolution.
For uproar! For dissent! For Reformation! For a thoroughly Disunited Kingdom!