THE TOULMIN METHOD:A MODERN VARIANT OF FORMAL LOGIC

EN101

Stephen Toulmin

• British philosopher and educator• Toulmin believed that for an argument to succeed, it

needs to provide justification for a claim. • This, he believed, will ensure it stands up to criticism and

earns a favorable verdict.• According to the Toulmin model, a claim is linked to its

support through what is called a warrant. • A claim’s warrant indicates how one gets from factual

support (which Toulmin calls data) to the claim.

Defining Some Terms

• Claim – is a sentence that asserts something that may be true or false and so needs support: The world is warming up. This is the best English class. Twinkies taste good.• Data or Reason – is a sentence supporting your claim,

main or not. It is generally triggered by the word because: Twinkies taste good because they have cream filling. • Warrant – what connects or bridges the data to the

reason. You might consider renaming this the “necessary assumption.”

An Argument

Brand A peanut butter has been proven to be healthier than Brand B. Furthermore, most children prefer the taste of Brand A to that of Brand B. Therefore, parents should choose Brand A over Brand B.

This seems like a fair argument on the surface. But is the person, who is claiming that peanut butter A is better than peanut B, assuming anything to reach his/her conclusion?

Sound Arguments as Buildings

Diagrammed

Brand A peanut butter has been proven to be healthier than Brand B.

Furthermore, most children prefer the taste of Brand A to that of Brand B.

Therefore, parents should choose Brand A over Brand B.

Parents should choose products that are healthier and taste better.

Revised Argument

Brand A peanut butter has been proven to be healthier than Brand B. Furthermore, most children prefer the taste of Brand A to that of Brand B. Parents should choose products that are healthier and taste better. Therefore, parents should choose Brand A over Brand B.

Does ArrangementMatter?

Parents should choose Brand A over Brand B. Brand A peanut butter has been proven to be healthier than Brand B. Most children prefer the taste of Brand A to that of Brand B. Parents should choose products that are healthier and taste better.

Another Argument

Environmentalist: When bacteria degrade household cleaning products, vapors that are toxic to humans are produced. Unfortunately, household cleaning products are often found in landfills. Thus, the common practice of converting landfills into public parks is damaging to human health.

The correct assumption?Environmentalist: When bacteria degrade household cleaning products, vapors that are toxic to humans are produced.Unfortunately, household cleaning products are often found in landfills. Thus, the common practice of converting landfills into public parks is damaging to human health. a. In at least some landfills that have been converted into public parks there are

bacteria that degrade household cleaning products.b. Converting a landfill into a public park will cause no damage to human health

unless toxic vapors are produced.c. If a practice involves the exposure of humans to vapors from household cleaning

products, then it causes at least some damage to human health. d. When landfills are converted to public parks, measures could be taken that would

prevent people using the parks from being exposed to toxic vapors. e. If vapors toxic to humans are produced by the degradation of household cleaning

products by bacteria in any landfill, then the health of at least some humans will suffer.

This is an attractive answer. However, just because a park has cleaning products doesn’t mean it has vapors from cleaning products. We still need the bacteria.

This is also a tempting answer choice. However, notice the language: “any landfill.” We’re concerned with landfills that have been converted to public parks.

The first premise says…

When bacteria degrade household cleaning products, vapors that are toxic to humans are produced.

cleaning products landfills parks have dumped into converted to vapors toxiclandfills parks to humans

bacteria + cleaning products = vapors that are toxic to humans

Wait a second! The author is assuming that these cleaning products will be degraded by bacteria. We need both cleaning products and bacteria in these parks in order to create the toxic vapors. This argument has a fundamental gap. The correct answer will be an assumption that fills this gap.

Diagrammed

When bacteria degrade household cleaning products, vapors that are toxic to humans are produced.

Unfortunately, household cleaning products are often found in landfills.

Thus, the common practice of converting landfills into public parks is damaging to human health.

In at least some landfills that have been converted into public parks there are bacteria that degrade household cleaning products.

A Diagrammed Example My college major should start a junior-year-abroad program. (Claim)

A junior-year-abroad-program will help the department establish international connections. (Data)

International connections would be valuable to my college. (Warrant)

Another Diagrammed Example The Washington Wizards are not good enough to make the playoffs. (Claim)

While the team has potential, it lacks maturity and depth. (Data)

Maturity and depth are required attributes of a playoff team. (Warrant)

Warrants• At the moment, this is all we need to be concerned with.• So, the warrant or the necessary assumption is what connects

the data to the claim. • Another way to remember the warrant is to picture:• But, more specifically, picture the following:

Data (Reason)Claim

Warrant

In-class and next class• Finish the following warrant worksheet. Read the claims and

data carefully. Don’t make unwarranted assumptions based on clichéd arguments or emotion. Reason well.

• Review the terminology handout for Tuesday’s class.• Keep working on your second essay.