Link to Council of Chalcedon, translated.
http://www.ccel.org/ccel/schaff/creeds2.iv.i.iii.htmlNotes from the website:
The Creed is preceded in the acts of the Council by an express confirmation of the Nicene Creed in both forms, 'the Creed of the three hundred and eighteen holy Fathers of Nicæa,' and 'the Creed of the hundred and fifty holy Fathers who were assembled at Constantinople.' The Fathers of Chalcedon declare that
'this wise and saving Creed [of Nicæa] would be sufficient for the full acknowledgment and confirmation of the true religion; for it teaches completely the perfect doctrine concerning the Father, the Son, and the Holy Spirit, and fully explains the Incarnation of the Lord to those who receive it faithfully.'
The addition of a new Creed is justified by the subsequent Christological heresies (Apollinarianism, Nestorianism, and Eutychianism). After stating it, the
Synod solemnly prohibits, on pain of deposisition 64and excommunication, the setting forth of any other Creed for those 'who are desirous of turning to the acknowledgment of the truth from Heathenism and Judaism.'
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The bolded part, the express prohibition and penalty of excommunication, is non-existent in V2 (as is the use of apostolic authority). Ergo, there is no penalty for challenging V2's docuмents, when they contradict each other and tradition. Ergo, they are not required to be believed for salvation. Ergo, they are fallible.