Evidence is a fact or piece of information that supports the veracity of a claim. 

Evidence is a critical aspect of an argument.  

Evidence is evaluated in terms of four criteria: 

  1. Relevance 
  2. Representative or Typicality 
  3. Sufficient 
  4. Accuracy 

Relevance: evidence should support the essay’s thesis or claim and be pertinent to the argument being made. 

Example: in an essay supporting mandatory HIV testing for all health care workers, one writer made the point that the spread of AIDS is at epidemic proportions.  To illustrate the point the point, the writer provided a discussion of the bubonic plague in 14th century Europe.  Why might that be a problem? 

Representative or Typicality: evidence should represent the full range of opinions about the subject and not just one side or the other.  You want a balanced and convincing discussion. In addition, the examples and expert opinions you include should be typical rather than aberrant 

If you argued against the use of animals in medical experimentation, you would not use just the information provided by animal rights activists. Why?   

Sufficient: there should be enough evidence to support the claim(s).  The amount of evidence required depends upon the length of your paper, your audience, and the nature of your thesis.  

Why would an author arguing for the validity of alien abduction stories require more evidence than one arguing against their validity?   

Accuracy:  Data shouldn’t be used unless it is accurate and up-to-date, and it can’t be persuasive unless the audience  believes in the writer’s credibility.  Faith in the accuracy of a writer’s data is one function of ethos. 

Evidence: Different Kinds 

Factual (Chester A. Arthur was the 21st president): The most commonly used type of evidence; may be drawn from your own experience but primarily drawn from research and reading. Facts are more convincing when supplemented by opinions, or interpretations of facts.   

Authoritative (expert testimony):  Not all opinions are equal. The opinions of experts are more convincing that are those of individuals with no specialized knowledge.  In the end, what is important is not just the quality of evidence but also the credibility of the person offering it.   

Personal/anecdotal (calling upon your first-hand experience), 

“Volunteering at the battered women’s shelter, I was constantly reminded of the emotional and psychological devastation wrought by spousal abuse on the most innocent of victims: the children.  In this time of slash-and-burn budget cuts, we must protect the social programs that protect our youngest and most vulnerable citizens. ”    

Statistical (graphs, surveys)   

“A 2001 survey by Nielsen Media Research found that 71 percent of the top 10 programs in 60 countries were locally produced in 2001, representing a steady increase over previous years. American movies on television still drew big ratings, grabbing 9 percent of the top 10 slots, but American dramatic or comedic series typically rated much lower than local shows.”   

Work Cited   

Kapner, Suzanne.  “U. S. TV Shows Losing Potency Around the World.” NY Times on the Web 2 Jan. 2003. 2 Jan. 2003 http://www.nytimes.com/2003/01/02/business/businessspecial/02TUBE.html. 

Logical Appeals (using inductive or deductive reasoning, or Toulmin logic)   

  • All books from the RU bookstore are used.  
  • These books are from RU bookstore.  
  • Therefore, these books are used.    

 Emotional Appeals (appealing to readers’ feelings)   

 Social/Ethical Appeals (appealing to readers’ sense of right and wrong)