Responding to a comment you made here, it is critical to think of Marxism as not being a moral philosophy. We can talk about moral motivations for one's activism and moral tones in the writing, but the philosophy itself is not grounded in moral assumptions and that is a core feature to what it is. The (imo somewhat unfair) dismissal of lumpen people is not about them being bad people but because another important element of Marxism is the way thay the specific relations of production in society creates a revolutionary class, and in this case that is a relation the lumpenproletariat is mostly alienated from.

But still a third vital element of ML philosophy is that neither Marx nor Lenin were prophets, and being a Marxist-Leninist does not mean following whatever they said, but instead using their basic framework, which one may decide leads them in some respects to different conclusions. It's a common ML stance that the past judgements about the lumpenproletariat were too limited and short-sighted, though their seperation from the rest of the proletariat does also represent a real difficulty in terms of organizing.

I'm going to hazard a guess that it comes down to political leverage. If the lumpen are those not engaged in productive labor, then they have little leverage on the system. Organizing and withholding labor is fundamental to class warfare.

I don't know the specifics about Lenin's take on the subject

But Marx was simply making observations about the dynamics taking place in British and western European slums in the middle of the 19th century

He wasn't making a universalist condemnation of lumpen segments throughout all time and space and he certainly wasn't talking about the global ghettos of the later 20th and early 21st centuries

The world Marx was exaimning was the world of Dickens, important observations at the time but not really relevant (in terms of this specific subject) 150 years later

The mechanisms that create, police and exploit slums have changed in significant ways since the time of Marx (hell they've changed multiple times) a decent Marxist examination of modern lumpen conditions can be found in Vijay Prashad's work on Indian communists and their struggles to organize the slums, it's a common thruline in all his lectures on Indian communism

To add to what everyone else here has said, the lumpenproletariat is less of "non-workers" and more "scabs and strike breakers". A class of proles that specifically work counter to the interests of their own class due to financial incentive from a controlling class.

Those who find a living outside productive labor are always going to be heavily vulnerable to financial exploitation. Not because they're bad, but because their position in the reserve labor army makes them now dependent on money from profit extraction.

Remember this concept was come up with well before anything even resembling a modern welfare system existed. In fact it was this relationship specifically that drove the Soviets and future revolutionary movements to immediately build welfare systems to prevent exploitation of lumpen/labor reserve.

Well, it's more a historical observation that still holds true today.

Thieves, pimps, general folks with high material struggles, these are all people that can be outright bought with money to do anyone's bidding.

They can be hired to kill or snitch or generally go against the interests of the proletariat.

There is no way the masses can satisfy the material needs of the lumpenproletariat in the same way that the bourgeoisie can, and so, the lumpenproletariat is much more easily swayed in favor of counter revolution.

I need to read much, much more about the lumpen but the term feels so extremely reductive, especially given today's conditions. Like I feel like there is a lot of potential within prison populations to build political consciousness, and other groups like sex workers and disabled folks, too. It's already happening within these populations anyway.

I think what people are missing is that the primary problem within the lumpenproletariat isn't that they aren't dissatisfied or alienated, it is that they do not possess the means through which to replicate themselves as a dominant class.

The reason the proletariat is necessarily the class that must overthrow the bourgeois in order for society to have social progression is that they have the knowledge and means to not only replicate society, but demonstratively alter it's material composition.

The lumpenproletariat, scabs, drug dealers, prostitutes, homeless, etc, the army of reserve labor, do not inherently possess revolutionary potential is because they, for the most part, predate the proletariat in existence, and are not directly connected to the way of shaping the world through material goods. It is the same reason why say, an email job does not produce an inherently revolutionary subject. It's not a moral calculus, it's a relationship to the means of production.

That said, it is not outside the bounds of a communist party to attempt to proletarianize the lumpen, in fact, that should be the goal.

The industrial proletariat is organized by the very nature of factory production and holds power over the productive forces, which allows it to develop class consiousness and be revolutionary. The lumpenproletariat is very individualistic due to fierce internal competition, doesn't control any of vital functions of the society, has zero class consiousness and can be easily bought, which means, that while some of its members will side with proletariat, lumpenproletariat as a class will find itself on the side of the bourgeoisie.

I think it's at least partially because you can't openly support criminal elements of society without alienating yourself from workers that want to see those elements of society eliminated (not the people themselves, the elements).

So you choose. Do you want to be the vanguard of the lumpenproletariat or the proletariat? If you can not be both then you must pick one.

Whether or not you can be both is probably determined by the level of consciousness and care for these people that exists within the proletariat, this will differ in various national conditions. The problem I notice is that the closer to revolutionary conditions a country tends to be, the less the proletariat tend to be sympathetic to the lumpenproletariat, usually because they are negatively affected by the lumpenproletariat's actions quite regularly. So while you might be able to get a very large number of society in somewhere like Norway to be supportive of the lumpen, that seems to also coincide with the fact the country is very far away from revolutionary conditions.

I always thought it was because

the lumpenproletariat spend all their time and energy on the capitalist treadmill (their life and their childrens' lives depend on it) so they don't have time to read theory, organize, or do anything at all really besides work. Once they see the revolution happening though they're totally on board, like in Cuba 1959.

But I'm learning a lot from the other responses, good question.