They are captivated not by realism, but by the sentimental, idealistic side of socialism, so to speak, its religious tinge, its poetry… secondhand, naturally.
Interesting pov of his philosophy that may be good to remember. Pyotr is probably as much of a dreamer as his father is, and indeed the revolution stared with a bad dream (the poem from 1.1.1 - Part I Chapter I Section I).