Keith Donnellan is an American philosopher who published notorious articles on the philosophy of language.
His concept of the difference between referential and attributive descriptions was proposed for implementation in Lojban.
|lo catra be la smit cu jai fenki|
Smith's murderer is insane.
- Attributive sense: the speaker says this without having any particular person in mind, basing his claim solely on the particularly brutal manner in which Smith has been murdered.
- Referential sense: Jones has been charged with the murder and has been put on trial, where his behavior is distinctly odd. The speaker (having Jones in mind) utters the same sentence.
- Attributive description. “A speaker who uses a definite description attributively in an assertion states something about whoever or whatever is the so-and-so.”
- Referential. “A speaker who uses a definite description referentially in an assertion ... uses the description to enable his audience to pick out whom or what he is talking about and states something about that person or thing.”
Implementation in Lojban
le catra be la smit cu jai fenki
The killer of Smith is crazy.
Attributive description is expressed using quantifiers and nibli:
ro da zo'u lo du'u da catra la smit cu nibli lo du'u da jai fenki
Whoever killed Smith, he is crazy.
Not using nibli leads to the two statements to mean the same but with different emphasis whereas nibli has outright different semantics.
lo itself is out of this philosophy.