What is the purpose of a thesis?
Smart people come up with them and they check if their answers are right compared to the scientfic answer. <--"Not exactly." It helps a reader understand a purpose of a written/typed paper.
The author's thesis is usually a statement that the author will spend the rest of the essay trying to persuade or prove to the reader how and why the thesis is valid. The author's purpose is the rest of the essay to prove the thesis statement. The author is trying to persuade the reader that the thesis is correct and valid and that is the purpose of the author's essay.
A thesis is a statement in which you take the whole argument in your essay and put it in your own words in a short sentence. there are two ways you can write your thesis: Specific topic + Attitude/Angle/Argument = Thesis or What you plan to argue + How you plan to argue it = Thesis the main purpose of a thesis is for your reader to ask questions such as "why", "how" etc.