The philosophy of Idealism.
Some philosophers think only the ideas in their minds truly exist. Nothing else exists. They say the "objective world", the world perceived by the senses, does not truly exist. They say ideas, or "subjective reality", are what truly exists. They say one should not perform activities. They say ideas alone exist. Nothing else exists in truth. Bishop Berkeley and other philosophers preached this philosophy of ideas, which is called "idealism". Mill accepted a modified version of this idealism.It is not correct to say that this "idealism" is the same as "spiritualism". When a person thinks about the information that came from his senses, those thoughts are called "ideas". The "ideas" that come in this way are only thoughts based on the material senses touch with the world of matter. These thoughts are not about anything beyond the world of matter. Gathering the light that filters in through the senses, the mind thinks. In this way ideas arise. Therefore "idealism" is not something above materialism. Among the impersonalists (advaitavadi) some say, "There is no God. There is no world. There are no living entities. All these are only ideas. Ideas are eternal and of great variety. These ideas will never cease to exist. Ideas are the absolute reality." This philosophy is very pathetic and foolish. Only a madman would be inclined to believe it. If we examine the lives of the philosophers who professed these opinions in their books, we will see that, as far as their actions went, they did not believe the "idealism" they preached.
It is not wrong to say that ideas are a subtle form of matter. Therefore this "idealism" must be counted among the different varieties of Materialism.
The philosophy of Skepticism
Some philosophers express this view: "Whatever anyone says to be 'true' is only 'true' temporarily. Therefore no truth is eternal and absolute. All truth is temporary and relative. What is considered true now will eventually be changed or refuted. At the end it will be considered untrue. Therefore the only unchanging Absolute Truth is the statement that there is no Absolute Truth." This idea gives birth to great laughter, for there is no truth in it at all. Only some professional philosophers, blinded by illusions and addicted to the tricks of logic, accept this foolish, illogical idea.
These philosophers accept the idea that truth is relative, that absolute truth cannot be. In the Bengali language this idea is expressed by the words, "Noyi hoy ebam hoyi noy." (It is not this. It is not that.) From this illogical idea the philosophy of doubts arise. In the English language this philosophy is called "Skepticism". Hume and other philosophers preached this idea. Although this Skepticism, or the philosophy of doubts, is unnatural and untenable, it has somehow been accepted by many philosophers.
The philosophy of material pleasures and the philosophy of cessation of existence (nirvana) brought great harm to their followers, and therefore the people in general became filled with horror merely to hear the names of these philosophies. Human nature is originally pure. It wears the ornament of devotional service to God. By following the philosophies of Materialism, human beings do not find happiness. In this way the philosophy of Materialism grabbed logic, shackled its hands and feet with hard iron bands and threw it into a dark prison cell. In order to cut its own shackles, logic thus created Skepticism, or the philosophy of doubts.
The Materialist philosophy holds that matters is eternal, and matter is all that exists. Professor Huxley preached this idea (the Perennial philosophy), and since then it has come from many other mouths also. These people say: "Without speaking of material causes and effects no true description of events can be spoken. No conclusions may be drawn that are not based on material causes and effects. At the end the words 'spirit' and 'love' will be cast far away from every book. Then the people will gradually become free to be carried away by the waves of Materialism. Then the idea of free will will be bound and imprisoned, and the truth that all activities are determined by material laws will be proved beyond any doubt."
When many people began to speak in this illogical way, human nature, seeing that it was about to fall into degradation, turned and began to walk on the path of a different philosophy. "This new philosophy will bring no bad results. Why not? Because it will destroy Materialism." Making this promise, logic gave birth to Skepticism, the philosophy of doubts. Skepticism threw the rubbish of Materialism far away. However, it also created another obstacle to stop belief in God. It made people doubt: "I do not have the power to see things as they really are. I see only some aspects of things. Where is the proof that I see things correctly? With my senses I perceive only certain aspects of things. With my eyes I perceive form, with my ears sound, with my nose smell, with my skin touch, and with my tongue taste. Through these five doors of knowledge I learn about the qualities of things. If I had more than five senses, if I had, perhaps, ten senses, I would learn other, different things about the objects I perceive. In this way I have gathers a little bit of knowledge with my senses, but it is knowledge riddled with doubts."
In this way, even though it destroyed the philosophy of Materialism, Skepticism did not help the cause of true Spiritual philosophy. Skepticism does not doubt the material world's existence, it merely says: "I do not have complete knowledge of things, and there is no way I will ever have complete knowledge. Therefore I will never understand things as they really are." At the end Skepticism refutes itself. If there is a genuine truth to be understood, then from what root does this philosophy of doubts grow? With careful thinking one will see that this philosophy of doubts is merely idle chatter.
"Do I exist, or not?" Who expresses that doubt? I do. Therefore i exist.
Excerpted from the “Tattva-viveka” of Srila Bhaktivinoda Thakura,
Commentary on verses 15 and 16.