Case grammar is the study of links between a verb’s contextual requirements and its valence. Valence is determined by the number of objects and subjects within a sentence. These subjects and objects are called arguments. The theory holds out that the verb determines its cases depending on number of agreements present. It should not be confused with grammar case, which indicates the grammatical form of a noun or pronoun.
Valence is important to the idea of case grammar. There are several different types of valence depending upon the number of subjects and objects. Both subjects and objects do not have to be present. When there are no subjects, such as “It’s snowing,” it is called an avalent. If there is just a subject or object, then it is a monovalent. Having both makes it a bivalent and having three is a trivalent.
Charles J. Fillmore created the case grammar theory in 1968 as part of his linguistic analysis studies. His theories formed a development on Noam Chomsky’s ideas regarding transformational grammar. Transformational grammar studies the differences between the surface structure of a sentence and its deep structure. Chomsky believed that multiple languages share basic ideas of deep structure, but these deep relationships between words and cases is hidden by their surface structure. The surface structure provides the outward meaning of the sentence.
Fillmore’s theory is that a verb chooses its deep cases. These deep cases can be used to study the surface structure of a sentence. A deep case is the agent, object or beneficiary of the verb. These are the arguments counted within valence. “Dave plays soccer” has a subject-agent, “Dave,” and an object, “soccer.”
The verb "sell" often requires there to be three arguments. “Sarah sold an apple to Jacob” has Sarah as the agent, the apple as the object and Jacob as the beneficiary. If the verb is changed to "buy," the sentence changes to “Jacob bought an apple from Sarah.” In this case, the roles of Sarah and Jacob are reversed so she is the beneficiary and he is the agent. In both sentences, the apple remains the object.
Verbs in case grammar, therefore, put themselves at the center of sentence structure. As well as indicating the agent, beneficiary and object, the verb in case grammar can also determine factors such as location, time and instrument. Using all of them could create a sentence such as “After lunch, Gerald cut the cake in two with a knife, so he could share it with Mary.”
Linguists such as Stanley Starostas and Walter A. Cook were inspired by Fillmore and took his research further. Cook spent the 1970s and 80s developing case grammar and using it to develop teaching methodology and linguistic analysis. Starostas developed the idea of “lexicase,” which applied case grammar to grammatical dependency.