You have to have three supporting claims that evidence that Cicero the author is speaking for the author Cicero himself. This could be used as a foundation:
Question. The specific question that I am going to address is: Does the character Cicero, speak for the author Cicero? Answer: And here is my answer for now: I do believe that the character Cicero speaks for the author Cicero, throughout the books of On the Nature of the Gods. Support 1. One of my supporting reasons is that book is based on different philosophers and one of those being Cicero himself. While all the philosophers argue about the existence of gods, Cicero claims ” I shall listen impartially and without prejudice. No compulsion binds me to defend any particular view willy-nilly” (Cicero 28). Being the only individual holding a neutral impression and is not siding with any of the philosophers, can interpret that he is speaking for himself.
Support 2. Another one of my supporting reasons is Cicero’s reasoning as to why he is interested in philosophy now and how he is questioned for it. Evidence for this can be found when he says “many found it surprising that I approved particularly of the philosophy which in their view doused the light and plunged the issues, so to say, in darkness, and that I had unexpectedly undertaken the defence of a school of thought which men had quitted and long left behind” ( Walsh page 5). Cicero character explaining himself about his sudden interest in philosophy can conclude that he is speaking for himself as an author. Support 3. Yet another one of my supporting reasons is that Cicero the author use’s Cotta’s character as a safety net for conducting the subject of skepticism, to protect the character Cicero, as he speaks for himself. Cottas and Cicero had similar ideals, but because atheism and agnosticism were dangerous subjects, Cottas character represented these subjects, as Cicero remains open-minded. Although Cicero’s open mindedness is left to be questioned due to the similar ideals between him and Cotta. evidence from this passage can be found in Book I of On the Nature of the Gods, when Cotta arrives to the conversation, Velleius claims that Cottas arrival is a reinforcement to Cicero because both of them have been taught by the same teacher Philo to know nothing, ( Walsh page 9). We can conclude that Cicero using Cotta as a safety net indicates that he is speaking for himself.