He joined the International Working People's Association (IWPA) and the Knights of Labor, within which he advocated for workers organization to push for economic reform and political revolution.

Lum was deeply affected by the Haymarket affair, as he was close friends with many of the defendants, including Albert Parsons, Adolph Fischer and Louis Lingg, the latter of whom he helped commit suicide in order to avoid execution.

After Haymarket, he moved away from advocating violent revolution and became more closely involved in trade union organizing, which he thought provided a means through which to achieve a free association of producers and anarchy.

[6] From an early age, Lum himself joined the abolitionist cause,[7] going on to voluntarily enlist in an infantry regiment of the Union Army after the outbreak of the American Civil War.

[21] From this position, he took a tour of the country, making a broad range of contacts, including socialists such as Albert Parsons in Illinois, Mormons in Utah and labor leader Denis Kearney in California.

"[28] Lum held the Federal government of the United States responsible, drawing attention to its "class legislation" which had prioritised railroad construction and military training, the latter of which made him consider whether armed revolution would be justified.

[34] In 1882, he published a pamphlet reporting on the federal government's repression of the Mormons' cooperative and voluntary associations,[35] which he argued had been done in order to extend American mining companies' holdings into Utah.

[40] Lum considered the time he lived in to have presented a revolutionary situation for anarchists, due to the power vacuum left by the collapse of the left-wing parties, the failure of legislative form and the rapid growth of industrial unions under the Knights of Labor.

[41] It was during this time that Lum first developed his anarchist political programme, which advocated for the organization of the working class, a refined revolutionary strategy, and a mutualist economic system.

[47] He predicted that this wave of unrest would soon erupt into social revolution: "From the Atlantic to the Mississippi, the air seems charged with an exhilarating ingredient that fills men's thoughts with a new purpose.

[50] Albert Parsons, along with George Engel, Samuel Fielden, Adolph Fischer, Louis Lingg, Oscar Neebe, Michael Schwab and August Spies, were arrested and brought to trial for what became known as the Haymarket affair.

[65] His apparently frivolous attitude towards the affair alienated him from others in the anarchist movement, with Spies' own wife Nina Van Zandt accusing him of "wishing their death", while Johann Most and Lucy Parsons thought him an insensitive "hair splitter".

[68] Benjamin Tucker's individualist group, already suspicious of such a strategy, distanced themselves from the revolutionary socialism of the Chicago anarchists,[69] stressing the differences between it and their own laissez-faire anarchism.

Although he still believed in the inevitability of revolution, he realized that the situation after Haymarket required a different strategy and called for efforts to be refocused towards propagating the principles of anarchist socialism.

[88] De Cleyre's anarchist philosophy developed further under Lum's guidance,[89] inspiring her to reject communist and collectivist anarchism in favor of mutualism and voluntaryism.

[95] After Alexander Berkman's attempted assassination of the Homestead plant manager Henry Clay Frick, Lum publicly defended the attack,[96] believing it was his duty to "share the effects of the counterblast his action may have provoked".

[64] At a public defense meeting in New York, Lum concluded that "the lesson for capitalists to learn is that workingmen are now growing so desperate that they not only make up their minds to die, but decide to take such men as Frick to St. Peter's gate with them.

[101] De Cleyre herself had come to reject violence and attempted to dissuade him, but Lum responded with derision, calling her "Moraline" and "Gusherine" and sarcastically saying "let us pray for the police here and the Tzar in Russia.

"[102] He remained determined to fulfill his "pledge" to the Haymarket martyrs, writing to De Cleyre one final time, on February 5, 1892:[103] I never lost sight of my purpose.

If done, and I think it will work, as we use chemicals, the responsibility will be assumed in posters on the walls.But Lum never carried out his planned attack, instead falling into a severe depression that left him unable to eat or sleep.

"[109] In her obituary on Lum, de Cleyre wrote that: "His early studies of Buddhism left a profound impress upon all his future concepts of life, and to the end his ideal of personal attainment was self-obliteration — Nirvana.

[126] But to Lum, these two reforms were insufficient by themselves; they additionally required the establishment of a free association of producers, which could counter the negative effects of industrialization, while maintaining economic progress and not resorting to a reactionary reversion to artisanal production.

Lum himself was closely involved in the organized labor movement, as he considered unions to be the best method for workers to combat class stratification and political repression.

[134] He argued for the Knights to pursue workers' cooperation and avoid electoral participation, hoping that the union could serve as a means to achieve a libertarian economic revolution.

[74] He later saw the AFL's craft unions as vehicles for advancing towards anarchy, promoting their voluntarism and supporting their campaign for the eight-hour day, while influencing them to adopt his own economic and political programme.

Political reforms brought by the Progressive Era made anti-statism less appealing, while the rise of the People's Party and the resurgence of the SLP overtook the movement's anti-electoral strategy.

[97] Only two months after's Lum's death, the Haymarket defendants were pardoned by Illinois governor John Peter Altgeld, who ordered the release of Fielden, Neebe, and Schwab from prison.

"[154] They were joined by Voltairine de Cleyre, Honoré Jackson, C. L. James, Lucy Parsons and William Henry van Ornum, but the conference was boycotted by Benjamin Tucker and Johann Most, who were still locked in an ideological conflict.

[157] Lum inspired de Cleyre to expand her philosophical outlook by reading from American, as well as European sources, with Thomas Jefferson's work particularly influencing her approach to anarchism.

She initially intended to complete Lum's mission of smuggling poison to Berkman, but eventually abandoned the idea and instead wrote him notes of encouragement, in which she refused to judge him for his actions.