 It is said that a philosopher is not a philosopher unless he differs from other philosophers. If one is to be a great philosopher, he has to defy all his predecessors. Scientists also work in the same way. If we try to find out whose statement is true, we have a great deal of difficulty. Therefore the Vedic sastras enjoin that we follow the personalities who have realized God, and therefore we follow Prahlada Maharaja, Dhruva Maharaja, Vyasadeva, Lord Brahma, Lord Siva, Kapila-deva, the twelve mahajanas, and their followers, the followers of Brahma's disciplic succession, the Brahma-sampradaya, the Rudra-sampradaya, the Visnusvami-sampradaya, the Ramanuja-sampradaya, and so on. If we follow the acaryas in the disciplic succession, our path is clear.
Syamasundara dasa: Descartes felt that because science is based on philosophical principles which have no basis in themselves, science is not worthy of our cultivation. He condemns people for using scientific technology to make more money. He said, "I am resolved no longer to seek any science other than knowledge of myself."
Srila Prabhupada: Yes, but he had no guru.
Syamasundara dasa: No, he didn't accept a guru. He accepted only what he could know through self-realization, the innate truths that he discovered in himself by meditation. First, he came to the understanding that I am, and later he concluded that because I am, God is.
Srila Prabhupada: That is a nice conclusion.
Syamasundara dasa: He had an obsession for the need of absolute certainty because he felt that all the conclusions of the philosophers before him were dubious. He believed that every idea must be subjected to doubt until the truth or falsity can be ascertained, just as a mathematical formula can be ascertained. Every idea must be subjected to cross examination.
Srila Prabhupada: But when will these doubts be finished? Your standard of understanding self-evident truths may be different from mine. So what is the standard? He must give some standard.
Syamasundara dasa: When Descartes meditated on the first philosophy, he concluded, cogito ergo sum, "I think; therefore I exist." He felt that everything was subject to doubt with the exception of the act of doubting itself. Since doubting is a part of thinking, the act of thinking is an undeniable experience. Therefore he concluded that because I doubt, I think, and because I think, I exist.
Srila Prabhupada: That is a good argument. If I do not exist, how can I think? But is he condemning doubt or accepting doubt? What is his position?
Syamasundara dasa: He accepts doubt as the only real fact. Because I can doubt that my hand exists, it may be a hallucination, a dream. I can doubt that everything perceived exists because it may all be a dream, but the fact that I am doubting cannot be doubted.
Srila Prabhupada: So what is his conclusion? Should one stop doubting or continue doubting? If I doubt everything, I may come to the truth and then doubt the truth.
Syamasundara dasa: His point is that the truth cannot be doubted, but that to discover the truth, we have to doubt everything. When we come to the truth, the truth will be undoubtable.
Srila Prabhupada: But how do you come to the truth if your business is simply doubting? How will you ever stop doubting?
Syamasundara dasa: Well, I cannot doubt that I am, that I exist. That truth is undoubtable. So he proceeds from there to the fact that since I exist, God exists.
Srila Prabhupada: Then his point is that by doubting, we come to a point where there is no more doubt. That is good. Doubt in the beginning, then the truth as the conclusion. But in any case, that doubt must be resolved. I doubt because I am imperfect and because my knowledge is imperfect. So another question is how we can obtain perfection. As long as we are imperfect, there will be doubt.
Syamasundara dasa: He says that even though I am imperfect, there exists perfect knowledge, or a self-conscious awareness of perfect ideas within myself. Knowledge of the perfect is innate within me, and I can know it through meditation.
Srila Prabhupada: That i