Nigel Irritable said:
I don't think that the DS can reasonably be considered "Trotskyist" in any sense. Opposition to the popular front and to taking office in popular front governments is a pretty basic Trotskyist principle. The decision of the LSSP to join the government in Sri Lanka for instance is generally taken as the date when they finally and decisively broke with Trotskyism. Although I suppose people insist on calling the SWP "Trotskyist" even though they reject pretty much all of Trotsky's core theories.
I think your central point is partially correct though. The DS was important to the USFI. It's their only substantial section in the third world or for that matter outside of Europe. It seemed to be having some success with the USFIs favoured tactic of joining a broad party and then sucking up to its leadership rather than forming a left opposition (see also Respect, Rifondazione etc). It was also the home of much of what passes for theoretical innovation in the USFI, most obviously the participatory budgets.
Not only was the DS an important point of prestige for the USFI, it's course was largely that which the USFI wants to follow elsewhere. The fact that its politics led to disaster was an uncomfortabe and embarrassing thing to face.
This is a crude and somewhat abstract 'frozen' analysis.
In Sri Lanka, a bourgeois party invited into government the marxist left, who constituted an independent party - the LSSP - with their own mandate and MPs, The president (Bandaranaike) was from a bourgeois party (the SLFP).
In Brazil, the Workers Party was clearly a mass party of the left and poor that won a presidential, but not a parlimentary majority, with the marxist left operating as a current within it, but without their own party and mandate. The PT was clearly a significant phenomenon - a single mass party dominating the workers movement with radical demands. Not at all comparable with the SLFP.
Once elected, the Lula leadership invited into government the bourgeois parties to gain a parliamentary majority. If anything, the analogy is Chile rather than Sri Lanka, as the left parties there (SP and CP) also failed to win a parliamentary majority, though Allende had won the presidency. In Chile, the 'Popular Unity' coalition was formally a popular front as it had bourgeois parties participating, the marxist left still worked inside it (I seem to recall Militant were rather keen on working in the SP at the time) and those who stood outside, like the MIR (Movement of the Revolutionary Left) were marginalised. Working inside a mass party however should not to be confused with endorsing the governmental programme (I can remember debates in the Labour Party about what position to take in 1977-79 about the 'Lib-Lab Pact' and of course we've had a side debate on the 'Social Contract'). But no-one on the left in Chile called for bringing down the government or refusing to support it, rather they called for the exclusion of the bourgeois parties, but also for the mobilisation of the class in defence of the government and its reform programme. Ultimately it was Allende's reliance on the loyalty of the army to the constitution (he appointed Pinochet don't forget) that was mistake, not particularly the machinations inside the government machine.
With hindsight I think it is clear the DS should have stayed in the PT and fought inside, but not taken ministerial portfolio. The FI leadership statement says they did have reservations. You may consider these inadequate but the fact is that it is clear the FI leadership and majority (internationally) are now strongly against governmental participation. In supporting the formation of P-SOL, they are showing they are prepared to split one of their largest sections rather than continue with the governmental participation.