Has the formation of linguistic states strengthened the cause of Indian unity?

Lets you argue that accommodating sub-regional languages within a linguistic State can deepen belonging, while noting it can spur competing demands.

• Tulu, a Dravidian language with a history of over 2,000 years, was reported as mother tongue by about 18.5 lakh people in the 2011 Census.
• Karnataka has made Tulu an additional administrative language in two districts, and it is already taught as an optional third language from Class 6 to 10 there.
• Days later the SDPI demanded similar status for Urdu, and leaders across parties are pressing for Tulu's Eighth Schedule inclusion.

Shows the unity versus imposition tension in language policy that still shapes Centre-State relations.

• The three-language formula dates to the National Policy on Education, 1968, after the Kothari Commission, aiming at national integration and mobility across States.
• Note that Tamil Nadu sees the formula as Hindi imposition, and Hindi-speaking States rarely teach a South Indian language as the 1968 policy intended.
• Article 350A directs States to provide primary instruction in the mother tongue for linguistic minority children.

The language settlement shows that accommodation rather than imposition kept a multilingual Union together, complementing the linguistic States argument.

• The Munshi-Ayyangar formula adopted on 14 September 1949 chose the term 'official language', not 'national language', for Hindi in Devanagari script (Article 343(1)).
• Article 345 lets each State adopt its own official language, and the Eighth Schedule grew from 14 to 22 languages via the 21st, 71st and 92nd Amendments.
• After the 1965 protests in Madras State, the 1967 amendment to the Official Languages Act continued English until every non-Hindi State resolves otherwise.