A thesis is an idea, stated as an assertion, that represents a reasoned response to a question at issue and that can serve as the central idea of a composition. A reason is an idea that functions to support another idea. Argumentative writing is a process of reasonable inquiry into the best grounds for agreement between a writer and an audience who have a mutual concern to answer a question at issue. Writing in an academic community is largely a process of finding and structuring reasons that can provide these grounds. It also provides a way of envisioning the potential major parts of an essay and the connections among them.
Form is generated by reasoning.
One need not rely on model forms to find the shape of one's essay. Style is like logic in that clarity and effectiveness depend not only on what is said but also on what assumptions about the reader are appealed to in the saying. Style is a matter of appropriateness. Revising is rethinking.