In short, the particular identity of someone whose attributes are partly known may be established through hearing, direct observation, or inference.
Knowledge of the entity described may be attained in several ways. Someone who knows the king’s description and then sees him may recognize his particular identity because of his established knowledge of the king’s attributes. He may also learn this from someone who tells him that the person bearing that name and description is this particular individual.
Thus, when an endowment deed or a similar document records the boundaries and attributes of a property, those boundaries may be established through direct inspection and inference, by determining that only these boundaries match those descriptions. They may also be established through reports and testimony, when witnesses testify that the boundary bearing the stated name and description is this particular one.
When witnesses testify concerning a person identified by name and lineage, and a judge communicates this in writing to another judge, or secondary witnesses testify to the testimony of the original witnesses, the particular identity of the person so named and identified becomes known—as when someone is identified in testimony by a lineage that no one else shares. If someone else shares it, however, his particular identity cannot be established by testimony giving his name and lineage. This then becomes like a physical description or characterization shared by more than one person. Whether someone’s identity may be attested solely on the basis of a physical description when necessary is disputed among the jurists.
Just as the particular identity of the entity described may be known in various ways, the initial knowledge of its distinguishing attribute may itself be attained in various ways. Knowledge of a particular entity may come through outward observation, through inward observation, or solely through its effects.
The jurists’ discussion of observed and described particular objects further illustrates the distinction between the particular and the universally applicable.
The item sold may or may not be individually specified. An individually specified item may be directly observed, in which case its sale is valid by consensus. Or it may be absent, concerning which the scholars hold three well-known positions, also transmitted as three opinions from Ahmad:
The first is that it is not