A paradox is a figuartive language device that makes an absurd statement, however, when further analyzed, can be proven or makes sense. This is what is happening here.
"I Have a Dream" is a public speech that was delivered by American civil rights activist Martin Luther King Jr. during the March on Washington for Jobs and Freedom on August 28, 1963, in which he called for civil and economic rights and an end to racism in the United States.