By defining democracy and democratic principles restrictively, the author has no problem knocking them down. I think people reaching a consensus through discussion and compromise is democratic, and that democracy need not be associated with majoritarian politics. I even think that it's democratic in character when people, as a group, reach a stalemate or defer their opinions and actions, waiting for a better time to take up a discussion again.
Well, it helps to understand the context that this pamphlet came out of. The 'Bordigist' fraction of the Italian social democratic party broke away to form an independent CP on the eve of the rise of Italian fascism. The aims were explicit: immediate seizure of the means of production by the working class, and if you look into what was going on at that time throughout Italy it was precisely the kind of 'deferment' within class-collaborationist parliamentary coalitions you describe that led to the destruction of the working class movement.
I have a problem with Bordiga's implied goal of a "unity of organization" and his "common direction" and so on and so forth. He describes a bottom-up "representative organization" (that apparently isn't democratic), but the more he describes it, the more top-down it starts to seem - he seems to assume that through the several elections of delegates into higher and higher tiers of government, the end result will be a party with the best interests of the whole in mind. This is an admirable goal! And it sounds democratic! And to some degree sensible, but the transference of wills from the many to the few seems just as imaginary as it would be in a more traditionally "democratic" representative government. (Have you read Michel's Political Parties, which argues the oligarchical tendency of political organizations?)
I'd agree with you with regards to problems in Bordigist organizational formulae, he was in some ways a faithful Leninist in this regard. But I agree with the general thrust that, formal considerations aside, the content of revolution and establishing class dictatorship is violently exclusive and not simply a matter of coordinating a mass of individual decisions. In his pamphlet A Contribution to the Critique of Political Autonomy(another great article exploring the various critiques of democracy), Gilles Dauve includes a short section on Bordiga that I think hits the nail on the head; Bordiga's organizational proposals were highly problematic, stemming from a teleological conception of revolution manifesting itself as a succession of 'stages', but he was right on in his approach of understanding/critiquing democracy as principle.
Bordiga says that "the revolution is a problem of content, a problem of the movement and action of revolutionary forces in an unending process, which cannot be theorized and crystallized in any scheme for an immutable 'constitutional doctrine,' " and it worries me when people have such pie-in-the-sky progressivist ideals, as if such a political organization would continually move towards something better rather than simply move. The organization he describes is one in which the supposed collective vision stamps out the wants and the needs of the individual in favor of an imaginary will of an entire nation. There is no will of a group, nation, or whatever. The closest you can come to the will of a group is to reach a consensus, and you don't reach a consensus when you suppress the voices of individuals - and I mean voice, not vote. That is, to have a say, and for what you say to matter to your group - this is an ideal not really at the heart of either majoritarian politics or collectivism.
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He emphasizes organizing based on what seems best at the time in pursuit of revolution, &c., but he doesn't take into account the trajectory and realities of any previous organization - he seems to think that the "content" of the revolution has more material political reality than the structure of it, as if the structure is this freewheeling, mutable thing, ready to change according to the whims of "us."
It's funny, given all the doubletalk in the essay, and given his promotion of military "defence" of "counter-revolutionary" "attacks" by, surely, people who would never be welcome in having a say in how their government should be run (because they don't promote the "revolutionary struggle"), that he says at the end that "democracy" is "tainted with irony for the exploited, oppressed and cheated." So he's not a Stalinist. So what.
I get what you're saying with regard to his faith in his own progressivist schema and dismissal of formal considerations, delinking them from 'content', but for all its flaws you can't really critique the piece out of context. I'm curious as to which other previous organizations' realities and trajectories you're referring to that he didn't take into account... this was written in 1921 in the midst of a severe crisis, revolutionary upheaval, and an increasing breakdown of civil society. I'm not sure if this pamphlet was written before or after the Kronstadt uprising was put down, but the Russian revolution had not yet entirely degenerated and was still arguably a beachhead for immanent world revolution. What organizational precedent had been set at this point in history? There were outbreaks of armed struggle going on in the streets at this point and counter-revolutionary attacks were not some ambiguous abstraction to be placed in scare quotes, additionally the critique of Stalinism that lead to the expulsion of the Italian and German/Dutch communist left from the Comintern was kind of a big deal with pretty severe consequences.
What is significant and prophetic about Bordiga's pamphlet is that it asserted the importance of an unyielding 'class-line'. It was an affront to bourgeois society and sensibilities at a historic crossroad, when a huge part of the workers' movement was being called into disarming parliamentary coalitions, it called for abstention from bourgeois democracy and the preparation for its forcible overthrow. Fractions of the ruling class were preparing to do the same, recruiting declasse sections of the 'middle classes' into fascist paramilitary organizations. All the while liberals, the right wingers in the communist movement, and social-democratic weenies were pleading for due-process and fine with sharing the table with capital in the name of 'democratic principles' but when the time came pull the reins in, the blackshirts didn't hesitate to put a bullet in their head.