Karl Marx's philosophies profoundly challenged capitalism through his critique of economic structures and social inequalities. In works like "The Communist Manifesto," he argued that capitalism creates a class struggle between the bourgeoisie (owners) and the proletariat (workers). Marx posited that capitalism is inherently exploitative, as it profits from labor while alienating workers from the products of their work. His ideas advocated for a classless society and inspired various political movements aimed at overthrowing capitalist systems, leading to significant societal shifts and the development of socialism and communism.