If you keep reading and skimming articles and books, you will find many different discussions and possibilities for writing topics. One way to do this is to write a list of binaries, a list of opposing ideas that may represent larger discussions about the topic at hand. Choosing from these opposing ideas in the text will lead you to ideas for a more specific argument. Scholars frequently engage in complex and long-lasting arguments that span across different journal articles and books. Professor X's article on climate change will be mentioned, discussed, or challenged by Professor Y in a book and Professor Z in another article. None of them are worried about saying things that have never been said before; the key is just to say them differently and perhaps better.