Can you trust our senses?

Why distrust our senses?

"Distrust your senses" has a very long tradition. Recall Plato's "cave" analogy from the early beginnings of philosophy, ~ 400 BC.

Plato postulated that there is a reality outside of what people experience. He compared the human "experience through the senses" to the experience of a caveman looking at a play of shadows on the cave wall: the caveman can only see the shadows on the wall, he / she has never experienced anything else and believes these shadows are all that there is of reality.

Plato says that there is a reality outside of it: for the caveman, there is someone or something outside the cave that projects these shadows. There's a sun (or something else) that provides the light, there's a whole world out there, but the caveman looking at flickering shadows on the wall may not even realize that the outside world exists. The cavemen's senses (and of course, analogously, every human's senses) can only say that "this thing here is a shadow" and "that thing over there is not". Plato's argument is that it doesn't matter how precisely our senses can see shadows on the wall: the argument is that there is a reality that is outside of what our senses can perceive.

It's not difficult to draw modern analogies:

Suppose someone was raised solely in Hollywood films from birth and had never seen the outside world. Would anyone be aware of the existence of scripts, cinematographers, sets, directors, actors, and people whose only job is to do makeup or lighting? Or would they assume that everything Hollywood showed them was reality?

Suppose I'm watching a movie and my senses are telling me that this guy they call the Joker is a very bad guy while this other guy called Batman is a nice guy and will save us all. What exactly does this sensory input (and my interpretations of it) tell me about reality?

Suppose we all live in the matrix and all of our sensory inputs are created by someone else for some (to us) unfathomable purpose. Is there any way that a "me" living in the matrix can see that my sensory experiences are different from an "me" living outside the matrix?

This is the basic argument of Descartes: How can my senses tell me whether I exist at all when a God somewhere dreams the whole world and we all live in God's dream?

Descartes famously replied, "I think that is why I am": when I have more or less control over my own thoughts, nothing else matters and I have an existence regardless of whether it is in a dream. (I'm not arguing whether this is a good or bad argument, I'm just saying that historical philosophers struggle with these questions. I can point out that Neo in The Matrix might very well ask himself the same thing. The external one Agent changed it from God to enemy AI, but the question remains the same.)

Say you live in the real world, but personally I happen to have a very good relationship with drugs and magic mushrooms, and every sense of mine tells me that an extremely lifelike dragon is attacking me right now. Should i trust my senses?

There are many reasons to distrust our senses in general, even primary sensory experiences like color and lightness. Illusionists, optical illusions, and drugs show that even the immediate senses can be deceived. Physics shows that there is a large part of the world that humans barely knew about: ultraviolet, X-rays, radio waves, radioactivity; None of this is directly perceptible to humans, but it is still real. Therefore, one cannot trust our direct sensory impressions too far. That is perhaps a more modern argument, and nowadays it is not difficult to find examples where our immediate sensory impressions are simply wrong.

Kant says that there is the "world as it is" that people can never really know, and there is the "world as it appears to me". We try our best to extrapolate our "here and now" limited sensory experience to rules that apply to the world in general, but we will never be able to know the "real" reality, we will only be simplified Knowing the Model We Have We built ourselves up in our minds due to our limited experience. And there isn't a lot of experience that lets us know everything.

The original philosophical argument of Plato 2500 years ago did not doubt any sensory impressions as such: the cave analogy assumes that the sensory impressions of the caveman exactly reflected the shadow play on the cave wall. The philosophical objection is that there could be a whole world outside of what humans happen to perceive for some reason that the viewer just doesn't know about.