He was a prolific writer, producing numerous articles, books, essays, and pamphlets on topics such as animal rights, ethics, evolutionary biology, humane education, humanitarianism, socialism, temperance, utilitarianism, and vegetarianism.

However, during his college years, Moore encountered Darwin's theory of evolution, which led him to reconsider his views, ultimately rejecting both Christianity and anthropocentrism and adopting vegetarianism.

He envisioned a societal and moral evolution that extended the same sympathy and fraternity that ended slavery and is now advancing women's rights to the humane treatment of animals.

[2]: 224 During this period, he lived on a farm south of Cawker City and worked as a reporter for The Beloit Daily Call, submitting rural correspondence about local events.

Acknowledging the challenge of changing minds in a single lecture, he described the horror he felt towards the "barbarous, blood-sucking practices" of meat consumption, linking it to broader exploitation where some beings' interests are sacrificed for others' convenience.

[17] In reply to Gronlund's critique, Moore asserted that for a carnivore, "every meal is a murder" and argued that explaining why one is "not a vegetarian" is essentially an attempt to justify being a predatory animal.

[2]: 225  It was highly praised by Lester Frank Ward, who commended its profound and independent thought, while David Starr Jordan lauded its bright style and bold conclusions, recommending it as essential reading for students of social progress.

It challenges the assumption that moderate alcohol consumption necessarily leads to negative outcomes, arguing that responsible use may have minimal or even positive effects on health.

The work considers the broader social and cultural contexts in which alcohol is consumed, advocating for policies that reflect scientific evidence rather than extreme measures like total prohibition.

[2]: 226  It was endorsed by notable figures, including Mark Twain, Jack London,[24]: 387  Eugene V. Debs, Mona Caird, Richard F. Outcault, and Ella Wheeler Willcox.

Moore accepted the challenge of changing anthropocentric perceptions, arguing that while such views have developed over the course of generations, both individuals and societies are in a state of constant growth and evolution.

[2]: 229  In the book, Moore analyses the theory of physical and mental recapitulation, which he termed "biogenesis", defining it as the process by which beings repeat the evolutionary development of their ancestors.

Moore called for a resurgence of true patriotism rooted in justice and humanity, decrying the moral decline and urging Americans to resist imperialistic tendencies and uphold the nation's original democratic ideals.

[29] In 1908, he denounced Theodore Roosevelt and his hunting expedition to Africa in an article,[2]: 228  describing him as having "done more in the last six months to dehumanise mankind than all the humane societies can do to counteract it in years.

Moore discussed a variety of topics, including, the advantages of vegetarianism, the cruelty involved in wearing fur, the merits of socialist candidates, and issues related to animal rights, ethics, women's suffrage, hunting, war, and alcohol consumption.

The Chicago Daily Tribune reported that Moore asserted Debs would target wealthy individuals for imprisonment rather than the usual victims who were populating prisons.

Moore argued that young people represented the greatest potential for advancing socialism and noted that university students were particularly open to socialist teachings.

In the speech, he claimed that vivisection and the consumption of meat are both a product of anthropocentrism and that Darwin's On the Origin of Species had made any notion of human superiority or uniqueness untenable and ethically indefensible.

[2]: 226 Howard Moore was one of the truest and tenderest of our friends, himself prone to despondency and, as his books show, with a touch of pessimism, yet never failing in his support and encouragement of others and of all humanitarian effort.

Moore first came to the attention of Henry S. Salt, co-founder of the Humanitarian League, and author of Animals' Rights: Considered in Relation to Social Progress, when he published Better-World Philosophy in 1899.

Moore reflected on his situation, stating that he detested writing and believed he could be relatively content if not for the constant pressure to produce literary works.

[2]: 228 In Salt's memoir, published in 1921, he expressed a belief that Moore had good reason for his suicide and was scornful of how timidly his death was covered in the majority of English animal advocacy journals.

You cannot go high enough nor low enough nor far enough to find those whose bowed and broken beings will not rise up at the coming of the kindly heart, or whose souls will not shrink and darken at the touch of inhumanity.

Just as prejudice towards different races and genders is condemned, Moore asserted that animals, being sentient and conscious, have the same entitlement as humans to fair treatment in ways that reduce their suffering and enhance their well-being.

Socialism, according to Moore, aimed to minimize the hereditary disadvantages imposed by the inanimate world and to create a more equitable society where the strong support the weak.

He saw this as aligned with the broader evolutionary processes of the universe, suggesting that the eventual establishment of a socialist society is not only desirable but also inescapable as part of the natural progression of life.

Relatives and friends, including his brothers-in-law Clarence and Everett Darrow, highlighted his kind nature, unwavering dedication to universal justice, and deep enthusiasm for educating young people.

"[54] Due to the sustained promotion and dissemination efforts of the Humanitarian League, George Bell & Sons and The Animals Friend, Moore's views were generally more widely accepted and readily embraced in Britain compared to the United States.

[65] Environmental historian Roderick Nash argues that Moore and Edward Payson Evans merit more acknowledgment for being the first philosophers in the United States to go beyond anthropocentric views.

[69] Mark Pittenger argues that Moore's racism was influenced by Herbert Spencer's The Principles of Sociology and that similar views were held by contemporary American socialists.