| Term | Definition |
| Testimonial statements | reports of the observations made by others. |
| plausibility and reliability | two important criteria limits observation by others use as assumed premises |
| appropriate statements by experts | identification, credentials reliability and lack of bias, area or expertise, and expert consensus. |
| appropriate identification | no expert is identified then it can not be used as an assumed premise |
| appropriate credentials | are the evidence that a person provides to show that she is an expert in a particular field |
| reliability and lack of bias | expert has history for not telling the truth and when they have reason to make statements that are not true. |
| appropriate area of expertise | a statement by an expert should only be used as an assumed premise if the statement falls within the expert's area of expertise. |
| expert consensus | if experts disagree about the truth of a statement, then that statement should not be used as an assumed premise. |