I discuss the relation between the logical classification into predicates and singular terms and linguistic word-class systems. An individual keeps track of a changing world. Input is from the world only. One individual helps another to keep track of a changing world by drawing its attention to properties. The second individual has access to the changed world.
Input is from the informant and the world.
One individual helps another to keep track of a changing world by drawing its attention to properties. The second individual has no access to the changed world. Input is from the informant only. This vocabulary may be either innate or learned. Such utterances can be more or less under volitional control.