Because human senses are not peerless indications of everything happening around you. Taking it to the extreme, there a whole lot of things a human cannot perceive. For example, butterflies can see into the UV spectrum, humans cannot, most bird species have the ability to see farther and with greater acuity than humans, whales can hear extremely subsonic while bats can hear much higher than human auditory range, the list goes on. Relying upon solely your senses, which are narrow in the grand scheme of things, is ignoring everything that is outside of what you can personally perceive.
How does what the senses don't report have any effect on the credibility of what they do? I'll grant you a hundred times over that some of our fellow creatures have broadened the scope of their senses for various adaptive purposes. But that's just additional sensory information. It does not mean that our sensory information is incorrect or flawed. Perhaps incomplete, but assuredly not inaccurate.
one time, in class, my professor had a big, shiny, reflective, silvery bowl, maybe a foot in diameter, sitting on the table. in the center of the bowl, sticking straight up into the air, was a small bundle of flowers. there was no water, so soil, NOTHING in the bowl except for these flowers that were upright and rising from the bowl. None of us could figure out how he had done it. why werent the flowers falling over without support?
then he invited each of us, one at a time, to come up to the bowl and put our hands in. this is the important part, so read carefully. each step we took closer to the bowl, from any point in the room, the flowers started to bend, and twist, and stretch. nothing dramatic, but definitely noticeable. by the time we reached the bowl to touch the flowers, we saw that they had never been standing at all. they were lying flat in the bottom of this big, mirrored bowl. had been the whole time. but ALL of us saw flowers standing straight up, without support, when we walked in.
that my friend, is called an optical illusion, and the human brain is extremely susceptible to them. all of us in my class SAW the flowers standing up, but when we touched them, they were laying down. two senses with conflicting information. which one was right? that's how we know that the senses are not necessarily credible.
Poll