This study tries to explain why Synge dramatized the happening of `slaying his da` (parricide). Among the various reasons stand out his biographical origin, the representation of the contemporary decadent mood and his wish to kill the British Empire as the father of Ireland. But we suggest that he designed the happening in order to describe the absence of paternity pervasive in his contemporary society. The eagerness for people in Mayo to overthrow the authority of the father figures is verified by their readiness to believe Christy`s story of his killing his father with one blow. They exalted Christy`s deed as a heroic one and enjoyed making a vision for him to save them with his bravery from the paternity-absent situation. But Synge does not imply that the vision will be realized. Christy`s `gallous story` turned out to be `a dirty deed` with his father`s showing up. To actualize the vision in people`s presence he struck his father stretched again, but contrary to his expectation, they attacked him harshly, which was the expression of anger with the ruin of their vision. In the meanwhile his father recovered himself and arranged to return home with Christy, whose attitude to his father exposed his resemblance to the very figure of the father he wanted to kill. In the end we are left with the fact that the father cannot be killed. It is Christy`s alleged lie that reminds us of Derrida`s difference. His gallous story maintains its gallousness by the temporal and spatial interval of the death, that is to say, till his father arrives to disillusion people. Repeated once more in front of them, the parricide cannot be achieved because of his father rising again himself and also in his son`s self, which confirms life/history is only the play between gallousness and disillusionment, the empirical errance of truths(signifiers) without the absolute truth(signified).