Marx famously called for “a ruthless criticism of everything existing” in his 1843 letter to Ruge. Even if you do not agree with Marx in many other things, there is something in here that actually functions as an endorsement of disagreement and skepticism. In the letter it says, in the Original:
“Ist die Construction der Zukunft und das fertig werden für alle Zeiten nicht unsere Sache; so ist desto gewisser, was wir gegenwärtig zu vollbringen haben, ich meine die rücksichtslose Kritik alles Bestehenden, rücksichtslos sowohl in dem Sinne, dass die Kritik sich nicht vor ihren Resultaten fürchtet und eben so wenig vor dem Conflikte mit den vorhandenen Mächten.”
and in English:
“If we have no business with the construction of the future or with organizing it for all time, there can still be no doubt about the task confronting us at present: the ruthless criticism of everything existing, ruthless in that it will shrink neither from its own discoveries, nor from conflict with the powers that be.”
There’s a reason it’s called the “left” – la sinistra, in Italian – the sinister side, not the “right” side, not the straight and narrow, but the other, the alternative, the deviant, creative, non-conforming, erratic, always critical, always critical of criticism, always irreverent part. Insults, hyperbole, aggressive argument (but no physical violence), joie de vivre, endless nights of spirited, no-holds-barred discussion, possibly lubricated with alcohol, THAT is what the left has always been. The chaos out of which a deconstructed order can grow. The cry of the wounded animal seeking healing.
This ruthlessness is an act of respect towards the other disputant. You treat the other person as the idealized version of themselves. You do not give false deference to somebody, you assume they can take it, not that they are weak (does that sound too Klingon? Marx would have loved Klingon blood wine and drink…)
No terms are agreed upon, nothing stands still, thinking never stands still, thinking always has multiple dimensions. There shalt be no orthodoxy. There shalt be no conformity. No collective. No agreement. No safe spaces intellectually, only physically.
Leftism is venal, is concrete, is bacchanalian, both generative and degenerate, both intellectually creative and destructive, but it is not crass – crass is crassism for its own sake. There is always a point to leftism: The destruction of dogma, the liberation of the individual mind, a ruthless and voracious education, and the utopian dedication to shaping a better future made up of a bunch of probably drunk belligerent intellectuals who like to lecture the “little people” on how best to join them, or at least to listen to them. But ideally, the more, the merrier.
Nobody excluded, no dogma, no thoughts forbidden, nothing too inconvenient, everything outright offensive, all language allowed, especially sarcasm, irony, fun, play, and deviance.
This is how the left as an intellectual movement can thrive.
But, sadly, there will always come a point where the creative, destructive, demonic, dialectic energy is contained, harmonized, dogmaticized, in order to bring the troops in line. Manifestos are written, party ideologues take over, discussion is streamlined, the nonconformists swapped out for the conformists, and the character of the “Left” disappears.
The happy catholic spectacle of radical theology (for what else is theology than unhinged philosophy?) turns into the frown-faced and dour eliminationist puritanism that will never tolerate an inconvenient thought. Whatever this new censorious regime of right and wrong, new left and alt-right, of good and evil may be, it certainly should not be called “left,” and it is heading nowhere good.
Personally, I don’t much care for too much causticity in dialog, and Marx’ personality certainly was not very, well, conciliatory. Neither is the talking down to the “little people” helpful. We need to be respectful of each other, and be inclusive of everyone. But respect does not survive well in a puritan thought-control environment either. There needs to be a middle way.