Through sense perception, inference born of logic and authoritative testimony knowledge is gained.
The mind moves in its circles, sometimes these movements move us towards clarity and understanding, sometimes they catch us and halt our evolution.
The first set of patterns the mind can move into are those associated with how we can acquire accurate, ‘correct’ knowledge.
This immediately raises the question of absolute truth, is there ever such a thing as ‘correct’ knowledge? Everything that we consider to be true is only true in the context of the information we have at present. Established truths are constantly changing as we acquire more knowledge that we consider to be authoritative. Probably the best example of this is our understanding of the cosmos. There was once a time the earth was flat and the stars in the sky were placed there as Hercules through his demons in to the heavens. Exploration and investigation have led to current thinking believing the earth is elliptical and the stars are balls of plasma held together by their own gravity. But these accepted truths will change and evolve as more information is gathered and our understanding expands.
At this point Patanjali is not concerned with what the truth or ‘correct’ knowledge is but with how we acquire knowledge. If the process of acquisition is flawed then the veracity of the knowledge is irrelevant.
The practical nature of the yoga sutras places the greatest authority on empiricism, knowledge gained through direct experience from the senses. The process of yoga clarifies the senses so that we can ever further collect more accurate information. Imagine the mind is a window. If the window is dirty we can’t see through it, we might see shapes or movement but we cannot identify what those shapes or movements are. Yoga cleans the window so we can see clearly, our senses (physical and psychological) become more refined and our understanding increases. This is Pratyaksa.
Once we can see, hear, feel things accurately how can we interpret the information we have gathered correctly?
Patanjali calls the most effective way of interpreting the information anumana, through the logical application of inference. In western philosophy this is called syllogism. For example:
All aliens are green.
Tim is an alien.
Therefore Tim is green.
The crucial elements of a syllogism are in understanding its limits. Because we know that “all” aliens are green if Tim is an alien he must be green. This will hold true until we find a yellow alien and then the syllogism cannot be applied, because we now know that not all aliens are green, some (at least one) are yellow.
It is also necessary that Tim is definitely an alien before we conclude he must be green, maybe he just looks like an alien? A syllogism also doesn’t work backwards, just because Tim is green doesn’t mean he’s an alien, he could be an unripe banana.
The reliability of applying logic depends on the reliability of the premises. Another example could be as simple as a literal application of “there is no smoke without fire”.
If the only circumstance in which smoke is produced is in the presence of fire then it follows logically that if there is smoke there must be a fire. Again this can only be logically true for as long as there is no other cause of smoke.
Patanjali is suggesting that we need to be able to apply these precise criteria in order to gain correct knowledge. However how does one know when one has purified the senses to physically see, hear, smell, taste, and touch free from bias? How can we know the syllogism we apply is flawless?
The third way of knowing is possibly the most ambiguous but also the easiest (in certain contexts) to access: Agamah, reliable testimony (verbal). Ambiguous because how do you know the testimony is reliable? First we need to know the person who is giving the testimony is reliable, they should be of irrefutable character free from blemishes, and they should have direct experience of that which they speak. The words of this trustworthy person can create a pattern in the mind of the listener and the citta will then flow into that pattern, facilitating a direct experience in the listener. Finding the trustworthy person is the crux.
Patanjali is writing in the post vedantic era, the concepts of the Veda are firmly established and there is an assumption of their knowledge and understanding in the Yoga Sutras. Yet whilst The Vedas placed the emphasis on ritual and the Upanishads shifted the emphasis to the experience of or searching for experiences of ParaBrahman, Patanjali is guiding us directly towards those experiences. There is no mention of any specific scriptures in the Yoga Sutras, direct experience of Iswara, ParaBrahman is considered to be the goal. Rather than learning about others experiences we should go and have our own.