'Pramanas' or Proofs are tools used by our intellect (Budhi). What are they?

Proofs in Hindi/Sanskrit are called ‘Pramanas’. Through logic or in other words, through proofs, we are able to sort out a problem and reach at a conclusion. When knowledge of a thing passes on directly to our soul through our sense organs or ‘MAN’, then that knowledge is said to be obtained through 'Pratyaksh Praman' i.e. direct cognitionKnowledge arising from 'Pratyaksh Praman' or direct perception should be unchangeable (If in the dark, a pillar is mistaken for a man but in the light, knowledge of man disappears and there remains in its place knowledge of a pillar, this shows that knowledge of the pillar was changeable),  convincing or dobtless and should not arise through words (Knowledge arising from a word is a subject of 'Shabd Praman' or verbal proof). When we know a thing through inference, then the knowledge so obtained is said to be through the Proof called ‘Anuman Praman’ or inference. (When we have a knowledge that two particular things happen together, then knowing one of those things through direct perception, we can know the other thing by inference). It is must that for knowing through inference, we must have knowledge of a part through direct cognition. But speculation about a thing is not covered by this Proof. This proof is of three types. Firstly, we may infer effect from a reason. For example, knowledge about rain by seeing clouds, knowledge of existence of education by seeing a student etc. Secondly, we may infer reason from the effect. For example, knowledge of rain on seeing increase in water of a river, knowlege about existence of father on seeing his children, knowlge about the existence of the creator (God) on seeing this organised world etc. Thirdly, we may infer a fact from a known law. For example, we know that the earth, the sun, the moon etc. move by seeing changes in their position (though we do not see movement in these bodies) by deducing from the law that nothing changes its place without movement. Third proof is 'Upman Praman' or comparison. When knowledge of a thing is obtained by comaring it with a well established fact of some other object. then it is said to be obtained through the proof of comparison.  This proof is very commonly used in our daily life to know a thing. For example, the liveliness of God can be understood by comparing it with liveliness of souls. When to reach at a conclusion, we use the words of some body as proof, those words are called ‘Shabd Praman’ or verbal testimony. According to the nature of the subject, we use the words of a particular person as evidence. For example, for a child, words of his father on a subject are proof for him and he uses these to prove a thing. Similarly, a person may use the words of a physicist as authority to prove a topic of physics. But only the Vedas come under the head authority as they are the words of God. The teachings of 'aapt' men ('aapt' men are those, whose lives are in consonance with the Vedas with regard to knowledge beginning from the earth right up to God) are also verbal testimonies. The Fifth Praman or proof is tradition or history. When we know a thing from a past event, then such knowedge is said to be obtained through 'Aitihay Praman'. Biograhy of a person is called 'Aitihay. Since, this proof relates to words about past, it can be included under the Proof-Authority or Verbal Testimony. The sixth Praman or proof is Presumtion. When our knowledge is based on corollary of another fact, then such knowedge is said to be obtained through 'Arthapatti Praman'. This Proof can be included in Anuman Praman. The seventh Praman or proof is Probability. Only that thing is probable which is in consonance with laws of nature. For example, birth of children without parents, being against the laws of nature is improbable. This Proof, too, can be included in Anuman Praman. The eighth Praman or proof is Negation i.e. a thing cannot be present where it is non-existent. This Proof, too, can be included in Anuman Praman.These are eight Pramanas or proofs. Fifth, sixth, seventh and eighth Pramanas or proofs can be included in the first four and thereby we are left with mainly four 'Pramanas' or proofs viz direct perception, inference, comparison and verbal testimony.