All objections below are selected from The Matrix as Metaphysics by David J. Chalmers. His response to and further note for each objection is, where necessary, summarized, rephrased, and used as objection to which my response is added.
Objection 1: It is true that a brain in a vat can think it is outside walking in the sun, when in fact it is alone in a dark room, by applying Descartes’ postulation.
My response: Descartes utterance that we have disembodied minds outside space-time, made of ectoplasm might be true. But consider when I say “I am in a coffee house”; I imply that I am actually in a coffee house. I would not say (either verbally or silently) “I am physically in a coffee house, but mentally I am in a library”. Thus, from the practical standpoint, the belief is still deluded.
Objection 2: An envatted being can think he is in Tucson, though he is not, is true. A rough analogy: My duplicate (he*) is now looking at Terry*, so its belief is true.
My response: For the belief to be true, first, there must be duplicates of people. The people he sees are not the real persons! Second, the first duplicate of him must match with the first duplicate of say, Terry; and the second duplicate of him must match with the second duplicate of Terry and so on up the scale. If there are several duplicates of Terry and him, and each duplicate must match with the duplicate of others of the same order level to arrive at the truth, there would be paramount confusion. This belief is thus deluded
Objection 3: Before he leaves the Matrix, Neo believes that he has hair. This is true because Neo is saying about his virtual hair, not real hair.
My response: This is how I know. - It seems that if a being is in the matrix, he would probably create more confusion for his life. For example, assume that he doesn’t have a thumb in his right hand before he is envatted. After being initialized into an envatted being, a thumb appears in his right hand in his virtual world (just like Neo has no hair in the real world but has virtual hair in the virtual world). Why should he think of having a thumb in his right hand in his virtual world when he doesn’t have it in his real world? To put it in a more probing way, could he wittingly make use of this matrix system as an alternative path, temporary or permanently, to dwell into a virtual world to shun from reality? If not, for what purpose?
Objection 4: All objects are made of bits. Virtual hands are not hands, but they exist inside the computer all the time. Virtual Tucson is not Tucson.
My response: Suppose a person is envatted and all the things he sees are made of bits in the virtual world. This is how a virtue world comes into being. But what about the smell of spicy foods, touch of cold and warm water, sounds of music, and the taste of wine etc? Are they still stimulating his senses with bits also? Does it mean that in the virtual world all these are missing or are they different in quality for appreciation? How would spicy food taste like?
Objection 5: I deny that the virtual world is nothing like we think it is. If we are in a matrix, we may not have many false beliefs, but even if we are not in the matrix, there is much knowledge about the fundamental nature of reality that we do not know.
My response: 1). Again, this is how I see it. - Human’s senses are created and configured to adapt only to our natural world. To be in the matrix, all senses would have to be changed to adapt to the virtual world. At one time, suppose a being is living in a real world and later on, due to frustration perhaps, chooses to live in a virtue world under the matrix system. This then brings up some interesting questions: Might this not be more confusing and troublesome for him to live in two different worlds, one is his natural world in which his body is dwelling and another world where all objects appear to him in bits, and he has to interact with both the envatted and unenvatted beings in his life? What is the real purpose of living in these two worlds? Isn’t our real world more beautiful and friendly where all our physical structures and sensory organs are wittingly built and marvelously designed just for us to appreciate all the wonder of our real world? The quality of appreciation of our real world might be different when the same sceneries are being processed by the brain of envatted beings.
2) If people are in the matrix, they could have more false beliefs than they are not in the matrix because the former may be under constant watch and control. There may be little or no freedom of thoughts and actions. Thoughts or ideas are built into their mind and programmed by the owner of the matrix system. If this owner is full of hatred, jealousy, aggression, and other negative qualities of the unenvatted human mind, then all envatted beings will be affected. And this subsequently influences the real world. Once beings are in the matrix, they might be prohibited from gaining further knowledge, or allowed to gain knowledge only pertinent to the wishes or desires of the programmer; thus, they probably stop improving altogether.