Getting Started
A strong argument is like a sturdy building: it needs a solid foundation. In writing, that foundation is your evidence. This chapter teaches you how to choose and explain evidence effectively by focusing on three key qualities: relevance, sufficiency, and credibility. Mastering this skill solves a common problem in student writing—paragraphs where the connection between the claim and the proof is weak, unconvincing, or unclear.
What You Should Be Able to Do
Evaluate whether a piece of evidence is relevant to a specific claim.
Determine if the evidence provided in a paragraph is sufficient to support its main idea.
Assess the credibility of evidence and explain how it impacts an argument's persuasiveness.
Write commentary that clearly explains the relationship between your evidence and your claim.
Select and use a variety of evidence types to build a more compelling argument.
Key Moves and Effects
The Three Pillars of Strong Evidence
In argument, evidence is the information—such as facts, examples, or expert opinions—used to support a claim. However, not all evidence is created equal. To be persuasive, your evidence must be relevant, sufficient, and credible.
1. Relevance
Relevance refers to how closely a piece of evidence is related to the claim it is intended to support. Relevant evidence directly proves or illustrates the point you are making. Irrelevant evidence, no matter how interesting, distracts your reader and weakens your line of reasoning.
How it works: Imagine you are arguing that your school needs a better recycling program. Evidence showing the amount of plastic waste the cafeteria produces each week is highly relevant. Evidence about the football team's winning record is completely irrelevant.
The effect: Using relevant evidence keeps your argument focused and logical. It shows the reader that you have a clear understanding of your own point and can support it directly, building your authority as a writer.
2. Sufficiency
Sufficiency refers to whether you have provided enough evidence to make your claim convincing. A single piece of evidence is rarely enough to prove a broad or controversial point. The amount of evidence you need depends on the scope of your claim.
How it works: A claim that one character in a novel is selfish can be proven with a few well-chosen examples from the text. A claim that an entire generation is selfish requires a much larger body of evidence, such as broad statistical data, expert analysis, and multiple examples.
The effect: Providing sufficient evidence demonstrates thoroughness and convinces the audience that your conclusion is not based on a fluke or a single, isolated case. It addresses potential skepticism and makes your argument feel comprehensive and well-supported.
3. Credibility
Credibility refers to the trustworthiness of your evidence. Evidence is credible if it comes from a source that is knowledgeable, unbiased, and reliable.
How it works: For an argument about the effects of climate change, a report from a team of international scientists is far more credible than an anonymous post on a social media forum. Credibility is established through a source's expertise, reputation, and lack of a clear agenda that would distort the information.
The effect: Credible evidence builds trust between you and your reader. When your audience trusts your sources, they are more likely to trust your argument and accept your claim.
Connecting Evidence to Your Claim with Commentary
Simply dropping evidence into a paragraph is not enough. You must explain its significance through commentary. Commentary is your analysis or interpretation that connects the evidence to your claim. It answers the crucial "so what?" question for your reader.
Good commentary does not just repeat the evidence in different words. It explains how and why the evidence proves your point.
Sentence Frames for Developing Commentary:
This evidence reveals that...
The fact that [summarize evidence] demonstrates the larger principle of...
This example not only supports the idea that [restate claim] but also implies that...
By showing [what the evidence shows], the writer highlights the importance of...
Data and Organization Tools
Use this matrix to test the quality of the evidence you plan to use in a paragraph. It helps you think critically before you start writing, ensuring every piece of information serves a clear purpose.
Evidence Evaluation Matrix
| Evidence | Relevance Check | Sufficiency Check | Credibility Check |
|---|---|---|---|
| Example: A statistic showing 80% of local business owners support a new downtown park. | Claim: The park is good for the local economy. Check: Highly relevant; it directly links business interests to the park. | Check: It's a strong start, but is it enough? I might also need evidence about increased foot traffic or property values. | Check: Where is the statistic from? A city-commissioned survey is more credible than a poll on the park's own website. |
| [Your Evidence Here] | Claim: [Your Claim Here] Check: How does this evidence directly support my claim? | Check: Is this one piece of evidence enough to be convincing? What else might a skeptical reader need to see? | Check: Who or what is the source of this evidence? Is the source knowledgeable and unbiased? |
| [Your Evidence Here] | Claim: [Your Claim Here] Check: Does this evidence prove my point, or is it just related to the general topic? | Check: Does this evidence represent a pattern, or is it a single, isolated instance? | Check: Could someone reasonably challenge the trustworthiness of this source? Why or why not? |
Device and Evidence Bank
A strong argument draws from a variety of evidence types. Using different kinds of support makes your reasoning more dynamic and persuasive.
Factual Evidence: Information that is verifiable and objective, such as statistics, historical records, or scientific data.
Anecdotal Evidence: A brief personal story or specific, observed example used to illustrate a point. It is often effective for emotional connection.
Expert Testimony: The use of opinions, findings, or quotes from a person or institution recognized as an authority on a subject.
Illustrative Example: A specific case or instance used to make a general or abstract idea more concrete and understandable.
Hypothetical Scenario: An imagined "what if" situation created to explore the potential consequences or implications of a particular action or idea.
Analogical Evidence: A comparison between two different things to highlight a point of similarity, often used to explain a complex concept in simpler terms.
Commentary that Clarifies: Explains what the evidence means in simple, direct terms to ensure the reader understands its basic significance.
Commentary that Amplifies: Extends the meaning of the evidence, showing the reader its broader implications or why it is more important than it might first appear.
Commentary that Connects: Links a specific piece of evidence back to the paragraph's main idea or the essay's overall thesis, reinforcing the line of reasoning.
Skill Snapshots
Here are three examples of a claim supported by evidence and explained with commentary.
1. Argument about Community Resources
Claim: Public libraries are essential for promoting economic opportunity in a community.
Evidence: A report from the city of Plainville indicates that its public library offered free job-seeking workshops to over 500 residents last year.
Commentary: This data shows that libraries provide far more than just books; they function as vital economic engines that empower individuals with practical, career-building skills. By offering these resources freely, the library directly contributes to the financial stability of its patrons and the overall health of the community's workforce.
2. Argument about School Policy
Claim: The implementation of strict school uniform policies can inadvertently stifle students' development of personal identity.
Evidence: An anecdote about a student who used her unique fashion choices to express her artistic inclinations but felt her creativity was muted after a uniform policy was enacted.
Commentary: While a single story, this student's experience exemplifies a common trade-off of such policies. By standardizing appearance for the sake of discipline, schools may suppress the very forms of personal expression that help young people explore and establish a unique sense of self during their formative years.
3. Argument about Personal Skills
Claim: Effective time management is a more critical skill for academic success than raw intelligence.
Evidence: A hypothetical scenario comparing two students: one is a genius but disorganized, frequently missing deadlines, while the other is of average intelligence but is methodical, planning their work and completing it on time.
Commentary: This comparison illustrates that potential is meaningless without execution. The ability to organize, prioritize, and consistently apply effort—all hallmarks of time management—translates directly into tangible academic achievement, often allowing a disciplined student to outperform a disorganized but more brilliant peer.
Common Misconceptions and Clarifications
Misconception: More evidence is always better.
- Clarification:Sufficient and relevant evidence is what matters. Piling on weak, repetitive, or irrelevant evidence can bore or confuse your reader, ultimately weakening your argument. Quality over quantity is key.
Misconception: Evidence speaks for itself.
- Clarification: Evidence never speaks for itself. You must provide commentary to explain how you interpret the evidence and why it supports your specific claim. Without commentary, the reader may interpret the evidence differently or fail to see its connection to your point.
Misconception: A personal story (anecdote) is not valid evidence.
- Clarification: Anecdotal evidence can be very effective for illustrating a point and creating an emotional connection with the reader. However, it is usually not sufficient on its own to prove a broad claim and should be balanced with other forms of evidence.
Misconception: Any number or fact is credible evidence.
- Clarification: Credibility depends entirely on the source. A statistic from a peer-reviewed academic journal is highly credible; a statistic from an unverified social media account is not. Always question where your evidence comes from.
Summary
Building a persuasive argument requires more than just stating an opinion; it demands that you construct a logical and convincing case for your reader. The strength of that case rests on the evidence you choose and how you explain it. By ensuring your evidence is always relevant to your claim, sufficient to be convincing, and drawn from credible sources, you establish a solid foundation of proof. Just as importantly, your commentary must build upon that foundation, explicitly connecting each piece of evidence to your line of reasoning. Mastering these skills will transform your writing from a simple assertion of ideas into a powerful and effective argument.