Evidence
- id: 1697804944
- Date: June 3, 2025, 9:15 p.m.
- Author: Donald F. Elger
Goals
- Describe evidence.
- Skillfully analyze and apply evidence.
- Get high positive payoffs for using evidence.
Evidence (What)
Evidence is information that provides a justified level of confidence—ranging from low to very high—that a claim is true.
Examples
| Claim | Evidence |
|---|---|
| The client is guilty. | DNA, fingerprint, eyewitness testimony, and motive. |
| The student has learned chemistry. | They can explain main ideas, solve textbook problems, and apply chemistry in many contexts. |
| Glue A is stronger than Glue B. | Five independent tests all showed Glue A was stronger. |
| The car’s battery is dead. | The engine won’t turn over, lights are dim, and a jump-start allows the car to start immediately. |
| The restaurant is good. | High customer ratings, long wait times, and consistent recommendations from trusted friends. |
Quality of Evidence
Evidence is not binary. It does not simply “prove” or “disprove” a claim. Instead, evidence exists on a continuum that ranges from low trust to very high trust. The trust level depends on how the evidence was produced, how reliable the method is, and how well the evidence supports the claim.
Low-trust evidence includes things like opinions, one-off stories, and unsupported claims. Medium-trust evidence comes from small tests, limited data, or partial indicators. High-trust evidence comes from systematic methods, strong measurement, independent verification, or direct recordings.
A claim by itself is not evidence. What matters is the information that gives us justified confidence—at any level—that the claim might be true.
The table below shows how the same claim can be supported by weak or strong evidence.
| Claim | Lower Trust Evidence | Higher Trust Evidence |
|---|---|---|
| Car gets 30 mpg | Friend tells me | I run a 10,000-mile mileage test and record the results. |
| Person didn’t commit crime | They say they are innocent | Video shows they were far away during the crime. |
| A supplement improves focus | Influencer says it works for them | A double-blind study shows a measurable improvement. |
| Student understands chemistry | They say they “get it” | They explain ideas, solve problems, and apply concepts correctly. |
| A restaurant is good | One person online says it’s amazing | Thousands of consistent reviews over years with a stable high rating. |