There seem to be altogether three aims or interests in this little Dialogue: (1) the dialectical development of the idea of piety; (2) the antithesis of true and false religion, which is carried to a certain extent only; (3) the defence of Socrates.
The subtle connection with the Apology and the Crito; the holding back of the conclusion, as in the Charmides, Lysis, Laches, Protagoras, and other Dialogues; the deep insight into the religious world; the dramatic power and play of the two characters; the inimitable irony, are reasons for believing that the Euthyphro is a genuine Platonic writing. The spirit in which the popular representations of mythology are denounced recalls Republic II. The virtue of piety has been already mentioned as one of five in the Protagoras, but is not reckoned among the four cardinal virtues of Republic IV. The figure of Daedalus has occurred in the Meno; that of Proteus in the Euthydemus and Io. The kingly science has already appeared in the Euthydemus, and will reappear in the Republic and Statesman. But neither from these nor any other indications of similarity or difference, and still less from arguments respecting the suitableness of this little work to aid Socrates at the time of his trial or the reverse, can any evidence of the date be obtained.