The document discusses the strength of arguments and persuasiveness of language. It introduces the concept of modality, which refers to the strength of word choices. Words are ranked on a scale of high, medium, and low modality. High modality words like "absolutely" and "definitely" are considered active words that make for a stronger, more convincing argument compared to low modality words like "possibly" and "probably" which are more passive. The document encourages using active words with medium to high modality in expository writing to strengthen arguments and persuade readers.