Propounding of astikāya in the context of order of the universe is a unique contribution of Lord Mahavira. Sānkhya's philosophy mentions Prakṛti (ajīva) and puruṣa (jīva), Buddhist mentions name and form, Vaiśeṣika describes nine substances, but, in Jainism the explanation of the order of universe is extended through the doctrine of astikāya. This is the unique explanation given by Lord Mahavira. Even the term astikāya is not found in any of the non- Jain philosophies. Though, Jain philosophy uses the term 'dravya (substance)', this term has also been used in Yoga, Vaiśeṣika and other philosophies with similar connotation. Buddhist (philosophy) mentions negation of Satkāyadṛṣṭi. Dr. Tatia opines that there is no clarity of the meaning of satkāyadṛṣṭi in Buddhist literature so it seems that Jain's astikāya must have been called satkāya over there. Astikāya is an indicator of eternal existence. Existence is momentary in Buddhist philosophy. That's why they negate the doctrine of satkāya.
Non-absolutism (Anekānt) is a significant and vital doctrine of Jain philosophy. Due to the acceptance of non-absolutism, many thinkers think that Jain philosophy accepts only relative truth and some critics have criticized anekānt on the basis of its relativity[1], but the truth is -without the acceptance of both absolute and relative truths, non-absolutism cannot be established. Acharya Mahapragya rejects all the criticisms about the acceptance of only relative truth in Jainism and opines- 'Some critics says that Syādvāda (doctrine of conditional dialectics) does not take us to the absolutistic truth and it is a midway rest-house in the journey for the ultimate truth, but this criticism is not factual. Syādvāda, really, takes us to the ultimate and absolutistic truth. According to Syādvāda, the world (cosmos) constituted by pañcāstikāya is an expression of complete and absolutist truth. All the five astikāyas have unique attributes and thus they have independent existence. Their existence, attribute and functioning cannot be explained by negating the relative outlook.'[2]
Dravya i.e. substance is absolute and paryāya i.e. modes are relative. This conception of astikāya has an important place in the world order.
Dr. Walter Schubring writes 'the concept of jīva-ajīva and pañcāstikāya is the legacy of Lord Mahavira. This is not a development of post canonical period.[3]