Weighing+the+Evidence

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toc =Measuring “persuasiveness”= Any claim — whether an argument, theory, or statement — can be analyzed for the quality of support it has through persuasive information (evidence). A tool for guiding this analysis helps a person to detect the flaws in each claim, using that knowledge either to strengthen the claim or to refute it.

Persuasiveness involves analysis of “Information” and “Warrants”. The claim must present valid Information that sufficiently supports (warrants) a belief that the claim is correct.


 * **//Claim//** = an assertion that a particular thing is true or correct
 * **//Information//** = collected facts and data about a particular subject (aka Evidence)
 * **//Warrant//** = the rationale or justification which supports a conclusion that the information (evidence) adequately supports the claim

Example:
 * **//Claim//** = Japanese internment during World War II was racist.
 * **//Information//** = Only U.S. citizens of Japanese ancestry were interned during World War II; U.S. citizens of German ancestry were not interned, even though there were more of them.
 * **//Warrant//** = The two racial groups were treated differently for no substantial reason; therefore, the real motivation was racist.

Analyzing Information and Warrants
In order for the claim to be adequately supported, both the Information and the Warrant must be tested. If the Information is invalid, even the most powerful Warrant won’t matter. If the Warrant is insufficient, even the most excellent Information won’t matter.

1. Testing Information: Reliability and Validity
Tests for information fall into two basic categories: · **//Reliability//** — the degree of certainty that the source of the information is trustworthy. · **//Validity//** — the degree of certainty that the information is accurate.



__Reliability__. The trustworthiness of the source involves questions such as:
 * What expertise does the source have in relationship to the information?
 * What biases affect the source’s presentation of the information?
 * Is the source a primary or secondary report of the information?

__Validity__. The accuracy of the information involves questions such as:
 * In what ways can the information be verified?
 * How does the age of the information affect its accuracy?
 * How complete is the information? What’s being left out?
 * How does the context in which the information was created affect its accuracy?
 * How does the nature of the information (factual, interpretive, or opinion) affect its accuracy?

Example: A historian reports that only U.S. citizens of Japanese ancestry were interned. How do we assess this information? //Reliability//: Does the historian have a reputation for solid research or expertise in this area? Does she have a bias on the subject? //Validity//: Did the historian check the internment records herself, or rely on someone else’s report? Have other historians investigated this issue and obtained the same set of facts?

2. Testing the “Sufficiency” of the Warrant
The warrant is the reasoning that explains how the information supports the claim. There are several tests for “sufficiency” or strength of the warrant, but all the tests stem from one basic question: Are the reasons that support the warrant stronger than the reasons which dispute it? Specific tests of the warrant include questions such as:
 * How directly does the information (evidence) relate to the claim?
 * How does the particular information (evidence) support the claim?
 * What general principles or assumptions are involved in tying the information (evidence) to the claim?
 * What reasons indicate that the information does not support the claim?



Pyramids built from individual Information/Warrant/Claim blocks
Every claim, whether implicitly or explicitly, is “warranted” by information. Once accepted, a claim //becomes// information; and this new information, with a sufficient warrant, can support a new claim. In this way, very complex arguments can be built from small bits of information. Likewise, the entire structure of a complex argument can be toppled by dismantling the warrant of just one claim within the structure.