"Leftist infighting" can mean many things, from very bad things to very good things. A thread.

When in Germany in the 1930s, the communists were fighting the 'social-fascists' (the socdem) and the 'trotsky-fascists' instead of making a united front against actual fascism, that was leftist infighting of the bad kind.

When Lenin presented his April theses, calling for all power to the soviets, and going against not just the liberals but also the SRs and many Bolsheviks, this was leftist infighting of the good kind: arguing a correct position and convincing comrades of it.

When Trotsky created the Left Opposition faction within the Bolsheviks, against the ongoing bureaucratization and the troika of Stalin/Zinoviev/Kamenev, this was also leftist infighting of the good kind.

When Stalin organized the Moscow Trials and later assassinated Trotsky himself, that was leftist infighting of the bad kind again.

Polemics and disagreements are not a bad thing. It is through discussion that we can arrive at better, more balanced, more precise, and stronger positions and programs. As long as the discussion happens in a comradely way, honestly and with an open mind.

It would be a mistake to try to avoid all such discussions because you consider them "leftist infighting". We want to change the world, and there are many potential ways to do that. Of course there will be disagreements, especially on tactics and strategies.

Of course when discussions become bitter, to the point that collaboration becomes impossible (or in extreme cases, you start killing comrades you disagree with), there is a problem.

After all, a left unity front will be necessary if we want to be effective. Unity does not need to imply uniformity: we can and should have unity in diversity, respecting differences of opinion, while fighting together for the 95% of things we do agree on.