The answer would seem to be brute forces. But brute forces could be the forces of an utterly irrational universe of chance, or the forces of a deterministic system. His thoughts and his bodily movements follow the same laws that describe the motions of stars and atoms. Mother nature appears to be Mama machine. If that is the case, the one thing that neither man nor any other being has is freedom.
Mechanical necessity rules all.
Good and evil would be words that men use because something in their brains has triggered them to think and speak in such terms, but ethical words could have no real content. The bare assertion that knowledge, ethics, and freedom exist cannot bring them into being, except in Russell's fervid imagination. Mama machine can only give birth to baby machines. If, to escape this problem, one should seek to find comfort in a world of chance, another view of the world suggested by Russell, he is not actually helped at all. Chance knows nothing of reason, ethics, or freedom.