In discussing the eligibility for beginners on the path of vaidhī bhakti, Rupa Goswami writes:

uttamo madhyamaś ca syāt kaniṣṭhaś ceti sa tridhā ||

There are three types [of adhikārīs]: uttama, madhyama and kaniṣṭha.

The uttama adhikārī is often confused with uttama bhakta or maha bhāgavata – perfected devotee- but the uttama adhikārī does not indicate a perfected bhakta here.  The word ‘adhikāra’ means eligibility. This eligibility is relevant for someone who is just beginning bhakti. Some people already have deep knowledge of the scriptures before they begin bhakti, i.e. before they take dikṣā from a guru. The Goswamis are examples of this- Rupa and Sanatana Goswami were already uttama adhikārīs before they surrendered to Sri Caitanya. Other people may have less knowledge of scripture. Accordingly, there are gradations of people who take to vaidhī bhakti. The classification above is not applicable to perfected devotees.

Vaidhī bhakti is performed because of faith in the meaning of scripture -śāstriya śraddhā. Naturally the eligibility for this bhakti is according to faith in the meaning of scripture. The uttama adhikārī has ‘prauḍha śraddhā’ – staunch faith, and this person is also śāstre yuktau ca nipuṇaḥ  – expert in logical understanding of śāstra. Such a person can defeat arguments against bhakti.

Jiva Goswami points out that such a person is śarvatheti tattva-vicāreṇa sādhana-vicāreṇa puruṣārtha-vicāreṇa ca dṛdha-niścaya – that is, his or her staunch determination comes from deliberation on tattva or tattva vicāra- that Kṛṣṇa is the worshipable deity, from sādhanā vicāra- that uttama bhakti is the best sādhanā,  and puruṣārtha vicāra- that the goal to be attained is Kṛṣṇa prema. This person is  very clear that it is Kṛṣṇa who is worshipable, that bhakti is the process and that prema is the goal. And the uttama adhikārī can prove this from śāstra.

The madhyama adhikārī has some knowledge of śāstra but the person may not able to argue as well as the uttama adhikārī. Many times, people get defeated in an argument but they dont change their views or faith. Similarly the madhyama may not be able to counteract or reply or refute the opponent’s argument, but still remains fixed in his or her own śraddhā.

An important point to note here is that this śraddhā is not sāmājik śraddhā – śraddhā that comes because one is born in a family of devotees, or because one’s social circle is that of devotees. It is śāstriya śraddhā – faith in the meaning of scripture- which is proportional to one’s understanding of scripture.

The kaniṣṭha’s śraddhā is komala- weak- such that their faith may get shaken upon hearing another argument or interpretation. But this will not last, and the person will eventually return to bhakti.

śāstriya śraddhā cannot change for either of these adhikārīs just by argument. This is the unique feature of śāstriya śraddhā.