One way that workers responded to these conditions was by organizing into labor unions. Another response was in many cases purely theoretical. Socialism, most famously Marxian socialism. I should probably point out here that socialism is an imperfect opposite to capitalism, even though the two are often juxtaposed. Capitalism's defenders like to point out that it's natural, meaning that if left to our own devices, humans would construct economic relationships that resemble capitalism. Socialism, at least in its modern incarnations, makes fewer pretenses toward being an expression of human nature. It's the result of human choice and human planning.