ON IGNORANCE – AJÑAANAM (अज्ञानम्) & AVIDYAA (अविद्या).
Ignorance or Ajñaanam (अज्ञानम्) is the complement of Jñaanam (ज्ञानम्). The latter implies knowledge, which is the subject of experience based on memory. Hence, Ajñaanam (अज्ञानम्) is interpreted as ignorance. But this is not the total interpretation. Actually, it is the limitation on knowledge. Vidyaa (विद्या) implies what is evident to a person, which is the knowledge on that subject. Hence Avidyaa (अविद्या) implies what is not evident to a person. Thus, these two terms: Ajñaanam (अज्ञानम्) and Avidyaa (अविद्या) are used interchangeably. To understand these concepts, we must understand the concept of Omniscience.
The Jain Philosopher Silanka says: There is no one with an outstanding intellect whose statements may be regarded as authoritative. Even if such a person existed (like Purana Kassapa or Makkhali Gosala or even the Buddha, as is generally claimed), he cannot be discovered by one with a limited vision according to the maxim: "one who is not omniscient does not know everything". He argues: “how can one desiring to know that a certain person is omniscient at a certain time do so if he is devoid of that person’s intellect, his knowledge and his consciousness”? Owing to the absence of the knowledge of the means, it cannot properly be accomplished because of the mutual dependence (of the two). Furthe: “without a super-knowledge (विशिष्टपरिज्ञान - visistaparijñana) the knowledge of the means is not attained and as a result there is no attainment of the super-knowledge of the object”. With a limited knowledge, no one can know that someone is omniscient
Omniscience is related to causality and time evolution. Of the three manifestations of time, only one – the present – is manifest. The other two are not directly manifest like present, but are related to it as cause and effect. Ever-shifting present is the effect of past that can be remembered and ever unknown future is the effect of present that can only be predicted. Without a past in the form of a cause, there cannot be a present and without a present in the form of a cause, there cannot be a future. So when we perceive the manifest present, we cannot deny the existence of the non-manifest past and future. But if one can break the barrier of causality, then everything will be manifest for him like present. That is Omniscience.
Since it is not possible for normal mortals to be omniscient, we are exposed to limited knowledge based on our past experience and the potency for acquiring and storing knowledge. The rest is ignorance. This creates various degree of knowledge/ignorance on different subjects in various people. This is one classification. There is another classification, based on its implication.
Our mental states are expressed through our thought (there are five mental states with five mental waves called alpha, beta, delta, theta and gamma. I have presented a paper relating these to the fundamental interactions of Nature. I am not discussing that here.) Thought (भावना) acts on the physical principle of inertia (संस्कार). Inertia of motion (वेग) is destroyed by special conjunction (including friction, which is conjunction with air or any other substance). Inertia of mind, i.e., thought, is destroyed by 1) begetting the substance of thought (प्राप्ति), 2) intense pain (कष्ट), or 3) by acquiring knowledge of the subject (ज्ञानम्). We initiate any effort only when we have the knowledge of some deficiency and how such deficiency could be remedied. This generates an inertia. This inertia is stopped by (among other things) knowledge. Thus, knowledge leads to both action and inaction. But once we know the true nature of the Universe, we get detached from everything (Eastern philosophy teaches detachment – to keep away to avoid problem, while Western philosophy does the opposite – to act in specific ways to get specific benefits). Thus, it leads to detached action that does not generate inertia of thought. A detached (विरक्त) person will not experience any deficiency. Hence, knowledge and action are considered an antagonistic couple. Thus, ignorance, which is the opposite of knowledge, is identified with action (कर्म).
Some people say that Ajñana is one of the nāstika or “heterodox” schools of ancient Indian philosophy (नास्तिक), and the ancient school of radical Indian skepticism (चार्वाकदर्शन). They consider it as a Śramaṇa (श्रमण) movement and a major rival of early Buddhism and Jainism. They hold that it is impossible to obtain knowledge of metaphysical nature or ascertain the truth value of philosophical propositions; and even if knowledge was possible, it is useless and disadvantageous for final salvation. They specialized in refutation without propagating any positive doctrine of their own (वितण्डा).
Only those ignorant of Vedic philosophy say that our knowledge of the Ajñana come from the Buddhists and Jain sources. The Ajñana view points are recorded much later in Theravada Buddhism's Pāli Canon in the Brahmajala Sutta and Samaññaphala Sutta and in Jainism’s Sūyagaḍaṃga. The sayings of Sceptics (ajñanikah, ajñaninah) have been preserved by Jain writer Silanka, from ninth century, commenting on the Sutrakritanga. Silanka considers "those who claim that skepticism is best" or as "those in whom no knowledge, i.e. skepticism, is evident" as sceptics. Apart from the specific technical meaning, Silanka also uses the word ajñanikah in a more general sense to mean anyone who is ignorant.