Everything we can perceive about the world comes in through our senses. There are many things about the world that we can’t perceive due to the limitations of our senses even when they’re working properly. Certain frequencies are too high or too low for us to hear, we can see only a small portion of light on the electromagnetic spectrum, and so on for our other senses. Additionally, most people have at least one sense that is deficient in some way, such as poor eyesight; everyone starts out with limited senses and anyone with one or more poor senses is at an even greater disadvantage.
However, all our senses do is gather information. Our brains receive that information and ultimately make sense of it. We can be shut off from information about the world if something goes wrong with our brains even when our senses are working properly. The question then becomes: how can we truly know anything about the world? If everything we can perceive about the world depends on our senses properly gathering information and our brains correctly interpreting it, then our knowledge ultimately depends on the trustworthiness of our brains. But how can we know our brains are trustworthy, especially when they can be fooled so easily through optical, auditory, and other types of illusions?
One might propose that we can compare our ideas about the world to the world itself and see if they match, but there is a problem with that. What use is comparing our ideas about the world to our perceptions of it in order to judge the reliability of our brains if the accuracy of our perceptions requires our brains to be reliable? Rather than providing a solution, this ends up taking us in circles without ever getting us closer to a definitive answer. Without some way to view the world objectively outside of our senses and our brains to test the validity of our ideas, we end up with only our subjective experiences to go by.
Michael Stevens covers this subject much better than I can in a great Vsauce video. This is interesting to think about and discuss with others, but, as Stevens says in the video, may frustrate some as it (as far as I know) doesn’t have any clear, objectively provable answers. Personally, I just enjoy thinking about it and don’t worry about its implications. What do you think about all of this? I’m interested to hear your thoughts about this subject if you’d like to share them.