Teaching Critical Thinking
Argument Structure

Argument structure refers to the way a main claim and sub-claims are related. Studying the structure of an argument allows one to understand how the argument is supposed to work, assuming that evidence is adequate. Sometimes parts of an argument are omitted because the writer or speaker assumes the audience will supply the missing parts. For instance, a speaker may present a piece of evidence without stating the sub-claim it is meant to support, in the belief that it is obvious and stating it would detract from the rhetorical force of the argument. However, analysis may reveal that the structure of an argument is flawed, because an essential sub-claim is absent or the inference from the sub-claims to the main claim is doubtful. In such cases no amount of evidence in support of the argument can establish the main claim.

Understanding and evaluating argument structure are sophisticated critical thinking skills. To help students develop these skills, it’s useful to lead them through a step-wise process.

Activities and Assignments
(L) Can be done in large section courses

Scrambled Outlines

Select an article or web site that presents an argument relevant to the course; outline the argument. Prepare a handout for students that scrambles the order of items in the outline. Have students read the article, then ask them to place the statements in the correct order. Students may work individually or in pairs. If wished, compare students’ responses to a key.  (L)

Partial Outlines

Select an article or web site that presents an argument relevant to the course; outline the argument. Prepare a handout for students that presents the outline, but with blanks where some items belong. Have students read the article, then ask them to fill in the missing items in the outline. Students may work individually or in pairs. If wished, compare students’ responses to a key.  (L)

Mapping Arguments

Ask students to draw a diagram of the argument as they understand it, using simple shapes to indicate the role of statements presented in the argument and arrows to indicate how they are related. For instance, one might write the main claim in a circle, sub-claims in ovals, and evidence in rectangles. If wished, compare students’ responses to a key provided by the instructor. (L)

Building Blocks

Have students read an article or visit a web site that presents a brief argument in support of a clearly stated claim. Ask them to write each “building block” in the argument on one line of a worksheet (below). When identifying building blocks, students should follow these guidelines:

  • A building block may be the main claim, a definition, a sub-claim, a piece of evidence, or a statement linking evidence to a claim (i.e., a warrant). Other building blocks are compositional devices—introductions, conclusions, illustrations, or transitions.
  • "Building blocks” may be single sentences or sets of sentences; paraphrase sets of sentences.
  • If a "building block" is repeated in an argument, write it down only once.

Alternatively, instructors can hand out the worksheet with the building blocks already completed for students.

Building Blocks (BB) Worksheet

Main Claim:
BB1:

What roll does this building block play in the argument?

  • definition or support for a definition
  • sub-claim: directly supports main claim
  • sub-claim: supports sub-claim BB#___
  • evidence: supports BB# ___
  • warrant: links evidence BB#___ to claim BB#___
  • compositional device
BB2:

What role does this building block play in the argument?

  • definition or support for a definition
  • sub-claim: directly supports main claim
  • sub-claim: supports sub-claim BB#___
  • evidence: supports BB# ___
  • warrant: links evidence BB#___ to claim BB#___
  • compositional device
BB3:
etc.

When students finish listing building blocks, ask them to identify which is the main claim; confirm that all students have selected the correct statement. Next, ask them to identify the function of each building block by checking the appropriate box and providing other information as needed on the worksheet. (Note: After students complete this step there may remain some evidence building blocks not linked to any sub-claim. This may indicate an implied sub-claim; have students write it on a separate BB line.) Discuss students’ responses; if wished, compare them to a key provided by the instructor. (L)