How would one approach writing the summation speech of Mr. Gilmer, the prosecuting attorney, to convince the jury to find Tom Robinson guilty,...

In a U.S. court of law, summation speeches are given first by the prosecuting attorney, which is Mr. Gilmer in Harper Lee's To Kill a Mockingbird, and second by the defense attorney, Atticus. One main goal of a summation speech is to summarize the facts and evidence of the case as they have been presented by the witnesses to the court. However, the main purpose of a summation speech is to persuade the jury to take the side of either the prosecution or the defense. To persuade the jury, both the prosecuting and defense attorneys will extensively use rhetorical devices in their summation speeches such as logos, ethos, and pathos.

Logos is an appeal to reason. The presentation of all of the facts of the case serves as logos. So, one thing you will want to do in writing your summation speech for Mr. Gilmer is summarize all of the details of the case as they were presented by both Mayella Ewell, the alleged victim, and her father, the alleged witness of the crime. For example, you would summarize the fact that Mayella asked Tom Robinson to cut up a chiffarobe, invited him into the house to pay him a nickle, and was attacked by Robinson inside her home. You would also summarize Ewell's statement that he ran when he heard her screaming and saw through the house window Robinson sexually assault Mayella.

Ethos is an appeal to ethics but it more specifically refers to the ethics of the speaker. If we are willing to see the speaker as a having "good sense, good moral character, and goodwill," then we are more likely to believe the speaker (Dr. John R. Edlund, "Ethos, Logos, Pathos: Three Ways to Persuade"). Pathos is an appeal to emotions. One thing Mr. Gilmer's summation speech would do is appeal to the ethical beliefs held by and the emotions felt by the members of the jury, especially those beliefs and emotions that align with his own, and, unfortunately, their senses of ethics and emotions are based on prejudiced beliefs.

In his own summation speech to the jury, Atticus actually reveals the prejudiced beliefs the prosecution is relying on to both build the prosecution's argument and persuade the jury. Mr. Gilman would develop his ethos and pathos based on these prejudiced beliefs. In his closing remarks to the jury, Atticus points out that the "witnesses for the state," meaning Mayella and her father, presented their testimonies with the assumption that their testimonies would never be questioned. More importantly, they made this assumption based on prejudices and the assumption that the members of the jury would agree with their prejudices; even the prosecuting attorney has based his line of questioning grounded on the exact same prejudices. We see Atticus lay out the fact that the prosecution's case was all based on prejudiced assumptions in his following remarks:

The witnesses for the state ... have presented themselves to you gentleman, to this court, in the cynical confidence that their testimony would not be doubted, confident that you gentleman would go along with them on the assumption--the evil assumption--that all Negroes lie, that all Negroes are basically immoral beings, that all Negro men are not to be trusted around our women. (Ch. 20)

Hence, in writing the closing remarks to the jury for Mr. Gilmer, the prosecuting attorney, you will want your words to reflect this unfortunate racist mentality because it is this racist mentality that will appeal to the jury's sense of ethics and emotional inclinations. Mr. Gilmer would speak forthrightly about the belief that "all Negroes are basically immoral" because he is confident that the members of the jury, as well as most of the spectators in the courtroom, would agree with him, which makes it his most persuasive argument.

All in all, Mr. Gilmer's closing speech to the jury would confidently express Robinson's guilt by first summarizing the details of the crime then referring to the commonly held prejudiced belief that all African Americans are immoral and tend towards criminal activity.