Just a single mistranslation out of focus could make the entire paragraph vague. The translation for "dominant" goes "primary" in Korean, so it made the whole paragraph vague. Realism is based on scientific views of things, while naturalism is on acribing the causes of things to genetics or the environment.
So if you saw a person who fell ill or poor, realists would just describe his current state, while naturalists would depict the reason to nature(environment) or his genetics.
That's why the term "dominant" was used to mean "naturalists wanted to reveal the dominant(the more powerful) states of things in all areas of life". If you have any comment on my opinion, please let me know.