Austin's thinking(which in the course of time came to be known as speech act theory was further developed and codified by the American philosopher John r searle, who had studied under Austin in the fifties, and subsequently became the main proponent and defender of the former's ideas• Austin’s thinking (which in the course of time came to be known as speech act theory) was further developed and codified by the American philosopher John R. Searle, who had studied under Austin in the fifties, and subsequently became the main proponent and defender of the former’s ideas