In European societies, knowledge is often pictured as a tree: a single trunk – the core – with branches splaying outwards towards distant peripheries. The imagery of this tree is so deeply embedded in European thought-patterns that every form of institution has been marshalled into a ‘centre-periphery’ pattern. In philosophy, for example, there are certain ‘core’ subjects and other more marginal, peripheral, and implicitly expendable, ones. Likewise, a persistent, and demonstrably false, picture of science has it as consisting of a ‘stem’ of pure science (namely fundamental physics) with secondary domains of special sciences at varying degrees of remove: branches growing from, and dependent upon, the foundational trunk.
Knowledge should indeed be thought of as a tree – just not this kind of tree. Rather than the European fruiter with its single trunk, knowledge should be pictured as a banyan tree, in which a multiplicity of aerial roots sustains a centreless organic system. The tree of knowledge has a plurality of roots, and structures of knowledge are multiply grounded in the earth: the body of knowledge is a single organic whole, no part of which is more or less dispensable than any other. ‘Stands an undying banyan tree,’ says Krishna in the Bhagavad-Gītā, ‘with roots above and boughs beneath. Its leaves are the Vedic hymns: one who knows this tree knows the Vedas. Below, above, its well nourished branches straggle out; sense objects are the twigs. Below its roots proliferate inseparably linked with works in the world of men.’
There is a right way and a wrong way to get this new picture of knowledge off the ground. An epistemic pluralist claims that just as a banyan tree has many different but equally valuable roots, so there are many different but equally valuable ways of interrogating reality. The wrong way to fill in the picture is to think that a ‘way of interrogating reality’ consists in a collection of what Paul Boghossian at New York University has called epistemic principles, general normative propositions that specify under which conditions a particular type of belief is justified. That is, we should resist any temptation to say, for example, that as modern science justifies its claims on the basis of observation and testing, so pre-modern societies justified theirs on the basis of divination and witchcraft, and each sort of epistemic principle is therefore just as correct as the other. That would lead down a slippery slope into relativism and social constructivism – to a forest of trees isolated from one another, and not to the single organic epistemic system that the image of the banyan tree represents.