The Toulmin Method

Identifying and Examining Evidence

Identifying and Examining Evidence

Once you have identified and examined the reasons supporting the claim in an argument, your next step is to examine the evidence which, in turn, supports those reasons.

Identifying and Examining Evidence for Reason One

The writer's first reason has to do with the danger of using herbicides. In support of this reason (in paragraphs 3 and 4), she offers several pieces of evidence:

Identifying the Evidence:

  1. In paragraph 3, a statistic (from her source, Bormann, Balmori, and Geballe) indicating how many pounds of herbicides and pesticides Americans use each year.
  2. In paragraph 4, her experience with the prevalence of lawn chemical use in Ohio.
  3. In paragraph 4, her reference to the yellow warning flags now used in Ft. Collins when lawns are being sprayed.

Examining the Evidence:

We must first ask ourselves, "Is this evidence sufficient?" That is, we must determine whether or not there is enough evidence offered to support the reason the writer is attempting to use. In this case, given the fact that the writer uses three different pieces of evidence (one from an "official" source and two from personal experience/observation), we could argue that she uses sufficient evidence.

Our second step is to ask ourselves, "Is this evidence credible?" In other words, can we trust the evidence the writer offers us? In this case, where the writer uses what seems to be a credible source (Bormann, Balmori, and Geballe's Redesigning the American Lawn), as well as fairly commonplace, believable personal experience, we could argue that she uses credible evidence.

Our third step is to ask ourselves, "Is this evidence accurate?" This is perhaps the most difficult step in examining the evidence, simply because we can't always be sure of accuracy without having the writer's sources in front of us or without having experienced what she has experienced. In this case, there seems to be no reason to question the accuracy of the evidence given, simply because it doesn't appear unrealistic or outlandish, and it has already been shown to be reasonably credible. Sometimes, however, you might suspect that the evidence offered in support of a reason is inaccurate, and that can be an excellent way to challenge an argument.

Identifying and Examining Evidence for Reason Two

The writer's second reason has to do with the cost of traditional landscaping in terms of money and time, and it is supported (in paragraphs 6-9) with several pieces of evidence:

Identifying the Evidence:

  1. In paragraph 6, statistics representing water usage (the writer's own and the average) in Fort Collins, along with information given in a phone interview with Laurie D'Audni of the Fort Collins Water Utilities.
  2. In paragraph 6, a statistic from her source (Bormann, Balmori, and Geballe) representing water usage in the West.
  3. After paragraph 6, the chart showing levels of water usage (the writer's own and the average) in Fort Collins throughout the year.
  4. In paragraph 7, lawn care experts' recommendation on how often fertilizer should be applied, and on how we "should aerate and thatch as well."
  5. In paragraph 7, personal experience--comparison of time and money spent in Fort Collins as opposed to Ohio.
  6. In paragraph 8: Cost of having lawn care professionally done.
  7. After paragraph 8, statistics on "Basic Cost per Season for Care of Bluegrass" and "Time Spent per Season in Basic Lawn Care"

Identifying and Examining Evidence for Reason Three

The writer's third reason has to do with the availability of alternative varieties of grasses which are more suited to the West. As mentioned previously, this reason is referred to throughout the essay, but it is treated most directly in paragraphs 10-13. Here is some of the evidence, given in different parts of the essay in support of the availability of alternative grasses:

Identifying the Evidence:

  1. In paragraph 5, testimony from two sources (Bucks and Meyer) as to the merits of buffalo grass and wheatgrass.
  2. In paragraph 10, the phone number of the county extension office, where readers can get information on species of grass suitable to our area.
  3. In paragraph 11, quotes from an article in the Coloradoan about the difficulties of traditional turf grasses and the availability of "a new variety of zoysia, Meyer Z-52).
  4. In paragraph 12, a claim that alternative types of seed may be ordered (and the approximate cost of the seeds).
  5. paragraph 13, suggestions of plants, shrubs, and flowers that thrive in the West.
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Introduction