Did Lord Vishnu speak in support of birth-based or conduct-based varna?

Question

Are there any instances of Lord Vishnu or any of his avatars speaking in favour of either conduct-based or birth-based varna?

Answer 1

Lord Vishnu in the form of Krishna says in the Bhagavad-Gita:

मां हि पार्थ ब्यापाश्रित्य येऽपि स्युः पापयोनयः।स्त्रियो वैश्यास्तथा शूद्रासतेऽपि यान्ति परां गतिम्॥

English Translation: For finding refuge in Me, O Arjuna, even those who maybe of sinful birth, women, Vaishyas and similarly Shudras, even they reach the Supreme goal. (Bhagavad-Gita 9.32).

I think the very word paapyoni makes it clear that He accepts the birth-based varna system. Also, He did not protest at all when Arjuna spoke ill words about the Varnasankaras.

Sri Krishna in Gita repeatedly stresses on obeying one's Sva-Dharmahe. Its meaning is dependent on the interpretation of the word "Dharma". In Gita, in most cases, Varnashrama-Dharma is meant by Dharma. For example, Sri Krishna says in the second chapter of Gita:

स्वधर्ममपि चावेक्ष्य न विकम्पितुमर्हसि।

धर्म्याद्धि युद्धाछ्रेयोऽन्यत्क्षत्रियस्य न विद्यते।।2.31

2.31 Even considering your own duty[Dharma] you should not waver, since there is nothing else better for a Ksatriya than a righteous[Dharmya] battle.

Then we move to to Chapter 3. Sri Krishna says to Arjun:

श्रेयान्स्वधर्मो विगुणः परधर्मात्स्वनुष्ठितात्।

स्वधर्मे निधनं श्रेयः परधर्मो भयावहः।।3.35।।

meaning 3.35 One's own duty [Customary or scripturally ordained observances of different castes and sects.-Tr.], though defective, is superior to another's duty well-performed. Death is better while engaged in one's own duty; another's duty is fraught with fear.

Please focus on the word "Swa-Dharma". According to Swami Jagadiswarananda (Reference: Srimad-Bhagavad-Gita, Udbodhan, page 95), this "Swa-Dharma" is made clear by Sri Krishna in the following slokas:

स्वे स्वे कर्मण्यभिरतः संसिद्धिं लभते नरः।

स्वकर्मनिरतः सिद्धिं यथा विन्दति तच्छृणु।।18.45।।

यतः प्रवृत्तिर्भूतानां येन सर्वमिदं ततम्।

स्वकर्मणा तमभ्यर्च्य सिद्धिं विन्दति मानवः।।18.46।।

श्रेयान्स्वधर्मो विगुणः परधर्मात्स्वनुष्ठितात्।

स्वभावनियतं कर्म कुर्वन्नाप्नोति किल्बिषम्।।18.47।।

सहजं कर्म कौन्तेय सदोषमपि न त्यजेत्।

सर्वारम्भा हि दोषेण धूमेनाग्निरिवावृताः।।18.48।।

meaning 18.45 Being devoted to his own duty, man attains complete success. Hear that as to how one devoted to his own duty achieves success.

18.46 A human being achieves success by adoring through his own duties Him from whom is the origin of creatures, and by whom is all this pervaded.

18.47 One's own duty, (though) defective, is superior to another's duty well performed. By performing a duty as dictated by one's own nature, one does not incur sin.

18.48 O son of Kunti, one should not give up the duty to which one is born, even though it be faulty. For all undertakings are surrounded with evil, as fire is with smoke.

I think in the context of all the slokas, the meaning of the words "Dharma" and "Swa-Dharma" becomes clear.

Yes,Swami Vivekananda was against the birth-based caste system. So we have both the views. So far as I know, Sri Ramakrishna accepted the birth-based Varna system. He says on 19 September 1884:

"A brahmin in spite of thousand limitations should be worshipped by all as he is born of the Gotras like Bharadwaja, Sandilya etc"(Kathamrita, Udbodhan,551). His oinion regarding this is clear in many other comments also.

So we basically have two different interpretations of the sloka: (a) the traditional view, which I think is clear from the above-mentioned slokas of Gita and comment of Sri Ramakrishna. (b) The modern interpretation given by Swami Vivekananda, one of the greatest sons India has ever produced according to many.

The choice is yours, of course.

Addition

According to Sri Krishna :

यः शास्त्रविधिमुत्सृज्य वर्तते कामकारतः।

न स सिद्धिमवाप्नोति न सुखं न परां गतिम्।।16.23।।

तस्माच्छास्त्रं प्रमाणं ते कार्याकार्यव्यवस्थितौ।

ज्ञात्वा शास्त्रविधानोक्तं कर्म कर्तुमिहार्हसि।।16.24।।

16.23 Ignoring the precept of the scriptures, he who acts under the impulsion of passion,-he does not attain perfection, nor happiness, nor the supreme Goal.

16.24 Therefore, the scripture is your authority as regards the determination of what is to be done and what is not to be done. After understanding (your) duty as presented by scriptural injunction, you ought to perform (your duty) here.

So Sri Krishna makes it obligatory to obey the scriptures. Its well-known that among the scriptures, the postition of the Smritis is higher than Itihasa and Purana. And according to Smritis, Varna ia birth-based.

Answer 2

Yes, according to the Vishnu Smriti:

Viṣṇu (16.1).—‘On women equal in caste to their husbands, sons are begotten who are equal in caste to their fathers.’