 Reichenbach expands upon Frege’s idea in his 1947. In addition to using an assertion sign, Reichenbach also uses indicators of interrogative and imperatival force. Hare similarly introduces force indicators to lay bare the way in which ethical and cognate utterances are made (Hare 1970). Davidson (1979), however, challenges the value of this entire enterprise of introducing force-indicating devices into languages, formal or otherwise. Davidson’s reason is that since natural language already contains many devices for indicating the force of one’s speech act, the only interest a force indicator could have would be if it could guarantee the force of one’s speech act. But nothing could do this: Any device purporting to be, say, an infallible indicator of assertoric force is liable to being used by a joker or actor to heighten the realism of their performance. Referring to the putative force-indicating device as a ‘strengthened mood,’ he writes,