Samkhya, also Sankhya, (Sanskrit: सांख्य, IAST: Sāṃkhya - Enumeration) is one of the six schools of classical Indian philosophy. Sage Kapila is traditionally considered to be the founder of the Sankhya school, although no historical verification is possible. It is regarded as the oldest of the philosophical systems in India. Most scholars agree that it was originally an atheistic school of thought. This was later incorporated as being one of the six astika (that which recognizes vedic authority) systems of Hindu philosophy with the major text of the theistic school being the extant Sankhya Karika, written by Ishvara Krishna, circa 200 CE. There are no purely Samkhya schools existing today in Hinduism, but its influence is felt in Yoga and Vedanta schools of philosophy. Its philosophy regards the universe as consisting of two eternal realities: Purusha and Prakrti; it is therefore a strongly dualist and enumerationist philosophy. The Purusha is the centre of consciousness, whereas the Prakriti is the source of all material existence.
The Sankhya school has deeply influenced the Hindu Yoga school of philosophy. They are sometimes referred together as Samkhya - yoga school.
Metaphysically, Samkhya maintains a radical duality between spirit/consciousness (Purusha) and matter (Prakrti). All physical events are considered to be manifestations of the evolution of Prakrti, or primal Nature (from which all physical bodies are derived). Each sentient being is a Purusha, and is limitless and unrestricted by its physical body. Samsaara or bondage arises when the Purusha does not have the discriminate knowledge and so is misled as to its own identity, confusing itself with the physical body - which is actually an evolute of Prakriti. The spirit is liberated when the discriminate knowledge of the difference between conscious Purusha and unconscious Prakriti is realized.
The most notable feature of Sankhya is its unique theory of Cosmic evolution (not connected with Darwin's evolution). Sankhya theorizes that Prakriti is the source of the world of becoming. It is pure potentiality that evolves itself successively into twenty four tattvas or principles. The evolution itself is possible because Prakriti is always in a state of tension among its constituent strands -
Sattva - a template of balance or equilibrium;
Rajas - a template of expansion or activity;
Tamas - a template of inertia or resistance to action.
All macrocosmic and microcosmic creation uses these templates. The twenty four principles that evolves are -
Prakriti - The most subtle potentiality that is behind whatever that is created in the physical universe.
Mahat - first product of evolution from Prakriti, pure potentiality. Mahat is also considered to be the principle responsible for the rise of buddhi or intelligence in living beings.
Ahamkara or ego-sense - second product of evolution. It is responsible for the self-sense in living beings.
Manas or instinctive mind - evolves from the sattva aspect of ahamkara.
Panch jnana indriya or five sense organs - also evolves from the sattva aspect of Ahamkara.
Panch karma indriya or five organs of action - The organs of action are hands, legs, vocal apparatus, urino-genital organ and anus. They too evolve from the sattva aspect of Ahamkara
Panch tanmatras or five subtle elements - evolves from the Tamas aspect of Ahamkara. The subtle elements are the root energies of sound, touch, sight, taste and smell.
Panch mahabhuta or five great substances - ether, air, fire, water and earth. This is the revealed aspect of the physical universe.
The evolution of primal Nature is also considered to be purposeful - Prakrti evolves for the spirit in bondage. The spirit who is always free is only a witness to the evolution, even though due to the absence of discriminate knowledge, he misidentifies himself with it.
The evolution obeys causality relationships, with primal Nature itself being the material cause of all physical creation. The cause and effect theory of Sankhya is called Satkaarya-vaada (theory of existent causes), and holds that nothing can really be created from or destroyed into nothingness - all evolution is simply the transformation of primal Nature from one form to another.
The evolution of matter occurs when the relative strengths of the attributes changes. The evolution ceases when the spirit realises that it is distinct from primal Nature and thus cannot evolve. This destroys the purpose of evolution, thus stopping Prakrti from evolving for Purusha.
This was a dualistic philosophy. But there are differences between the Samkhya and other forms of dualism. In Western philosophy the main focus of discussions about dualism concern dualism between the mind and the body. In Samkhya, however, it is between the self (purusha) and matter, and the latter incorporates much of what Western thought would normally refer to as "mind". This means that the Self as the Samkhya understands it is more transcendent than "mind". It is sometimes defined as 'that which observes' and the mind is the instrument through which this observation occurs.
Samkhyan cosmology describes how life emerges in the universe; the relationship between Purusha and Prakriti is crucial to Patanjali's yoga system. The evolution of forms at the basis of Samkhya is quite unique. The strands of Sankhyan thought can be traced back to the Vedic speculation of creation. It is also frequently mentioned in the Mahabharata and Yogavasishta.
Sankhya also has a strong cognitive theory built into it; curiously, while consciousness/spirit is considered to be radically different from any physical entities, the mind (manas), ego (ahamkara) and intellect (buddhi) are all considered to be manifestations of Prakrti (physical entity).
There is no philosophical place for a creator God in the Sankhya philosophy; indeed, the concept of God was incorporated into the Sankhya viewpoint only after it became associated with the theistic Yoga system of philosophy.
Sankhya serves as the main opponent of Vedanta Philosophy which elucidates the monistic theory of creation. For the Vedanta schools, Brahman is the cause of this world. Sankhya denies that vehemently as material world that is insentient cannot originate from a sentient element.