An important question arises with respect to the evidence of knowledge. When one claims to be in possession of knowledge about a statement of fact, how should he verify about the existence of that very knowledge in himself. Epistemology defines knowledge to be justified true belief. The question relates to the method of verification as to whether one really knows the stuff which he believes that he knows.
Let us take an example. Suppose a person claims that he knows that fire burns. Obviously then, as a prudent person, he should never put his fingers in fire. The very fact that he keeps on putting his fingers in fire is a sufficient proof that he does not have the knowledge that fire burns. If one does not put his fingers in fire then it cannot be logically deduced that he has the knowledge that fire burns but if one puts his fingers in fire then it is sufficient proof of absence of this knowledge. The logical formulation is as follows:-
X = I have the knowledge that fire burns.
Y = I don’t put my fingers in fire
Naturally X ⇒ Y and therefore ~Y ⇒ ~X. However, ~X does not imply ~Y.
Thus, if my knowledge of say α implies my non-doing of β and yet I am seen to indulge in committing β, then it can be safely inferred that I don’t have the knowledge of α.
Therefore, it is safe to state that evidence of knowledge is conduct.
In this background, let us examine our conduct vis-a-vis the statements which we claim that we know. As knowledge presupposes belief, non-existence of belief will obviously imply absence of knowledge.
A Vedantin states that everything is one. He claims that he knows it or believes in it. And yet he is seen to suffer attachment and aversion. Here, we are talking from his own perspective and not from the point of view of others. If I claim that I know the unity of existence and thus I claim that I believe in it, then logically I cannot suffer from attachment or aversion for everything is one. The very existence of attachment and aversion in me proves that I don’t have the knowledge of unity of existence.
ब्रह्म विद्या presupposes सत्त्व शुद्धि i.e. purity of heart which in turn requires performance of शास्त्र विहित कर्म with ईश्वरार्पण बुद्धि. It also requires non-performance of शास्त्र प्रतिषिद्ध कर्म. The very fact that one enjoys performance of शास्त्र प्रतिषिद्ध कर्म proves beyond doubt that he doesn’t possess purity of heart. Logically therefore he cannot claim to possess ब्रह्म विद्या either. Thus, one’s own conduct is an evidence of existence/absence of one’s knowledge.
What does the term purity of heart connote. It means a heart which is free of at least लोभ, मोह, काम, क्रोध, मद, मत्सर. It should also be free of violence. It should contain दया, क्षमा, प्रेम etc. Only if the heart has such qualities that the ब्रह्म विद्या can dawn. And to get such a heart in no joke. It can be attained only after 24×7 conscious hard work. And hard work of only शास्त्र विहित कर्म. Also, not even a single act should be शास्त्र प्रतिषिद्ध. And on top of all this, these should be done with ईश्वरार्पण बुद्धि.
Phew! Let us admit that the effort required is phenomenal and only rare persons having single minded devotion to this cause can accomplish it. Let us also admit that any talk of ब्रह्म विद्या till then remains a mere intellectual exercise. There is a word of caution here though. Pursuit of ब्रह्म विद्या is helpful even before the attainment of purity of heart ONLY IF the aspirant is honestly and sincerely making efforts to accomplish सत्त्व शुद्धि.
In nutshell, one should keep examining oneself critically and check as to whether or not he is relishing the performance of शास्त्र प्रतिषिद्ध कर्म. If one stops the performance of शास्त्र प्रतिषिद्ध कर्म, even though by force, that itself is a great effort. But to keep doing शास्त्र प्रतिषिद्ध कर्म, with or without guilt, and to talk of ब्रह्म विद्या is simply useless and infructuous.
Therefore, the talk of ब्रह्म विद्या is useful only if it is coupled with sincere and honest efforts to attain सत्त्व शुद्धि.