Jain Metaphysics and Science: 2.5 Kala (Time)

Kala possesses the characteristic of 'persistence - through - change' and, therefore, is a substance. Its existence is necessary to define the duration (continuity), change (modification), motion, newness and oldness of substances. Time by itself cannot cause a substance to exist, but continuity of existence implies duration in terms of time. Mutation or change or modes also cannot be conceived without time, because change implies temporal succession in which modification takes place. Similarly, motion implies different positions of an object in space in temporal succession. Lastly, time causes the distinction between the old and the new, the 'before' and the 'after'. kala is not astikaya i.e. it does not have spatial extension. Only the 'present' mode of kala is in existence, the 'past' has expired and the 'future' is yet to come. The singular present' kala cannot have spatial extension.

Kala is of two types - the absolute kala and conventional kala. The absolute kala assist modification/ change in substance and the conventional kala measures the duration of change. The Swetambara and Digambara traditions differ in the interpretation of absolute kala. According to Swetambara view since the absolute kala assists the substances like jiva - and pudgala in their modification it should be an attribute of the substance it is assisting. Thus the need of a separate substance like absolute kala is dispensed with. The Digambara concept of absolute kala is very different.  According to this view the absolute kala is in the form of kalanus (paramanus of kala) which are placed one each on each pradesa of loka. The kalanus are separated from each other and therefore there is no spatial extension. The number of kalanus is equal to the number of pradesa (innumerable) in the loka. A kalanu assists the substances present on its pradesa in their modification. kalanu itself being a substance follows the rule of origination - cessation - permanence.

The concept of conventional kala is same in the two traditions. The smallest indivisible unit of conventional Kala is 'samaya'. One 'samaya' is the time taken by a  paramanu moving at a medium pace to go from one akasa pradesa to the adjoining pradesa. All other units of conventional kala are multiples of 'samaya'. These practical units of conventional kala are based on the movement of sun and moon.

Ghari, muhurt, month and year are some practical time units described in Jain philosophy. According to Jain philosophy the motion of sun and moon is observed in a limited part of middle loka and therefore there only the conventional time is defined. The standards of conventional time so obtained are used for measurement of intervals of duration in other regions of loka.