Caste is by definition a closed social system whose membership is acquired by virtue of birth. Rules of endogamy and restrictions on social intercourse between castes helped to maintain the insularity of such groups.
From purely Brahmin point of view, it appears as if this system was rigid and closed. However, when we examine historical data ranging back to the Vedic period we find that in reality there existed a lot of flexibility. Social mobility with the gain of economic and political power was always present.
The caste system, therefore, was a dynamic reality having a great degree of flexibility in terms of internal structure and functions. Social mobility of caste system has been an important feature.
By social mobility we understand the process by which individuals or groups move from one social status to another in the social hierarchy. Social mobility can be either upward or downward.
Sociologists observe that in spite of the closed nature of caste system, there have been changes in caste hierarchy and its norms from time to time. Caste mobility as a process of social and cultural change has been explained by Srinivas in his concept of sankritisation. Sanskritisation is a process whereby low Hindu caste changes its customs, rites, rituals, ideology and way of life in the direction of high and frequently twice-born castes. This has paved the way for mobility to occur within caste system.
Besides sanskritisation, westernization was also instrumental in the mobility of the caste system.
The notion of hierarchical gradation of caste groups drawing legitimacy from religion and the concept of purity and pollution has changed with the passing of time. The structural distance between various castes defined in terms of purity and pollution has been changed.
The ideology of caste prescribed specific occupation for specific caste groups which had a specific place in the social hierarchy. The vocations of the upper castes were considered to be the most prestigious while occupations of the lower castes to be polluting.
The advent of the British saw new economic opportunities flowing out and reaching the masses. Caste monopolies enforced by family inheritance came under attack. Ownership of land provided principles governing wealth and a yardstick by which the local prestige system was measured. The low caste thus was able to surmount the obstacles posed by tradition. They began to participate in the economic process. Market economy, daily wages, and hired labour eroded steadily the functioning of the traditional jajmani system. Bailey in his study of Bisipura village has shown how certain low caste groups flourishing in the wake of new business opportunities invested their profits in land. The breakdown of the traditional economic system and the Sincreased economic status of lower caste groups undermined the Brahmin dominance especially in Tanjore, Tamil Nadu.
Before the introduction of democracy, the upper caste persons were playing a dominant role in the village panchayat which was quite different from the concept of morder panchayat. They decided the disputes within the village. In villages traditional caste panchayats and leaders were powerful means of social control. The advent of democracy and decentralised politics in the form of the three-tier Panchayati Raj system, witnessed politics carried down to the grass-root level. Caste became a prominent variable in electoral politics.
The decline of the traditional economic systems, caste-free occupations and mobilisation of caste groups have all resulted in the decline of the traditional political role of castes. Yet we find that caste retains its political significance. This is evident, for example, in the case of political mobilisation of caste groups in Madhopur, U.P. In this village, the ranks of Noniyas, the salt-makers and Chamars, the leather-makers, joined hands in opposing the locally dominant upper castes. The situation is same in other states such as Karnataka, Gujarat, Maharashtra, M.P. etc. It is not politics that gets caste-ridden, it is the caste that gets politicised as says, Rajni Kothari.
It is important to mention here that no social change can bring about total changes in the society. It is found that the traditional social organization exemplified by the caste system has undergone several changes. Mobility of caste system has been an important feature. Yet it continues to exist in Indian society performing some old and some new functions.