Human senses have limitations and cannot detect beyond a certain threshold of external stimuli. However, we humans possess intelligence that enables us to create instruments and allow us to perceive beyond the limitations of our senses.
Flat-Earthers argue if our senses cannot perceive a thing, then it does not exist. In reality, the instruments we made enable us to detect many things that our senses cannot.
References
- Thresholds for the Perception of Angular Acceleration about the Three Major Body Axes – The National Academies Press
- Absolute threshold – Wikipedia
- Human eye – Wikipedia
- Absolute threshold of hearing – Wikipedia