Final answer:
Frederick Douglass uses the complexity of emotions and understanding of enslaved individuals, as well as the personal and social consequences of slavery, to prove that slaves are men with sophisticated thought and acute awareness.
Step-by-step explanation:
The student's question asks what evidence Frederick Douglass uses to support his assertion that slaves are men. In his narrative, Douglass provides evidence by highlighting the sophistication of thought and acute awareness that enslaved people possess, despite the dehumanizing conditions of slavery. He argues that slaves have the capacity for complex emotions and understanding, as shown through their ability to recognize the harm slavery causes, not only to themselves but also to their oppressors.
One particular example is his discussion on the consequences for children born from the union of slave women and white masters, revealing the intricate social and personal detriment caused by slavery. By doing this, Douglass affirms the humanity of slaves contrary to the prevalent belief of his time that regarded African slaves as less than human.