https://courses.lumenlearning.com/englishcomp1/chapter/analyzing-arguments/ 

Analyzing Arguments

Sometimes an argument will have an unstated or suppressed premise, rather than stating something outright.

Example: Unstated Premises

Consider this highly unscientific poll conducted by a TV news station. “Which do you believe the senator is most out of touch with: illegal immigration, border security, or the American people?” The pollster is operating as if it is unquestionable that the senator is out of touch with something. In other words, the question presupposes that the senator is “out of touch.” However, this unstated premise is debatable once it is brought out into the open. 

A reader or listener unaware of unstated or suppressed premises may unknowingly accept an argument on unfair terms. On complex issues, assumptions people take for granted often need the most scrutiny.

Example: Missing Premises

In the claim, “This medication is labeled as totally natural, so it is safe for me to take,” the hidden premise—that natural means safe—is questionable and should be critically examined.

Argument Diagramming

Besides recognizing the use of induction and deduction, you can use diagramming or outlining to identify it an argument’s structure.  An argument, in this context, is not a “quarrel” or a “fight”, but a set of statements where premises support a conclusion.

The first step is to pinpoint the main claim (conclusion) and the supporting claims (premises). This process is easier when the author clearly signals argument steps using “indicator” terms that highlight premises and conclusions.

When diagramming or outlining an argument, use indicator terms to identify the conclusion and premises, especially if the argument’s flow isn’t clear. Since a conclusion can appear anywhere—beginning, end, or in between—we cannot tell whether a statement is a conclusion simply by where it is positioned in the argument. 

The Purpose Behind Diagramming an Argument

Diagramming or mapping an argument serves two key purposes:

• It helps you clearly understand the other person’s argument by identifying its logical structure, allowing you to assess its strengths and weaknesses before deciding whether to accept it.

• It strengthens your analytical skills, helping you organize and present your own arguments effectively when taking a position on an issue.

Steps in Diagramming an Argument

Here are the basic moves that are required to create a clear diagram or outline of an argument.

• List the Claims – Identify all claims in the argument. Since a sentence may contain multiple claims, break them into separate statements and use a numbering or labeling system.

• Cut the Fluff – Remove repetitions, unsupported assertions, and irrelevant information to focus on the core argument.

• Find Premises and Conclusions – Determine which statements serve as premises (supporting points) and which is the main conclusion (the overall claim being defended).

• Spot Sub-Conclusions – Identify any sub-conclusions, which act as conclusions for smaller arguments but also serve as premises supporting the main conclusion.

• Distinguish Independent vs. Linked Premises – Identify whether premises stand alone (independent) or work together (linked) to support a conclusion. If diagramming, find some way to connect linked premises together before connecting them to the conclusion.

Using the Argument’s Paragraphing to Evaluate the Premises

An author must carefully organize their material to guide the audience through their argument, and one key tool for this is the paragraph. Each paragraph should be tightly focused, with sentences that collectively develop a single idea, often introduced in a topic sentence. The paragraphs themselves should follow a logical order that reflects the structure of the argument.

Since premises are the key steps in an argument, a well-structured essay may use each premise as a topic sentence, with supporting sentences developing the idea. Sometimes, a single premise may guide multiple paragraphs, each exploring different aspects of the claim. For example, if a premise states, “College students overestimate the amount of binge drinking that occurs,” the argument might include separate paragraphs analyzing how this overestimation differs among sorority members, fraternity members, and non-Greek students.

Look to see whether the author has used paragraphing-by-premise to organize their argument and outline its structure for the audience.  Also, consider whether any key premises are missing. Some premises may be suppressed—assumed but not explicitly stated—either because the author takes them for granted or hopes the audience won’t question them. As you analyze the argument, identify any unacknowledged premises and determine where a paragraph addressing them should have been included.

The Similarity Between Conclusions and Thesis Statements

When we talk about a paper, we usually talk about the paper’s main claim as being its thesis statement. But of course, a paper that just makes a claim or states an opinion but offers no supporting reasons or arguments is not much of a paper. We would be bothered by reading an editorial in which someone stated a strong opinion on some public issue yet did nothing to justify that opinion.

When an author supports a thesis with reasons, then the thesis statement can be described as the conclusion of an argument, with the supporting reasons being that argument’s premises. The argument now has a structure that can be outlined or diagrammed.

Adapted from "Analyzing Arguments" by Lumen Learning, which is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).