He thinks, therefore he doubts

The first thing I noticed upon reading Descartes' meditations was the parallel between his logical philosophy and the inquisitive nature of the Scientific Revolution. Years of history classes have taught me that the Scientific Revolution was a time of extensive expansion in physics, biology, chemistry, and the like, as well as a reliance on observable that could be put through what would later be deemed the Scientific Method. It was no longer acceptable to believe in doctrines that failed to provide proof for their claims. It's interesting that this skeptical and curious mindset was so strong that it seeped into the era's philosophical output. Descartes takes this critical examination to an extreme, suggesting that there may be "...absolutely nothing certain". He claims that our senses can often mislead us, and there is certainly truth to that. Optical illusions, for example, exist in abundance, all of which manipulate the faults within our visual system. If our hearing becomes impaired, sound localization and distance perception become more difficult to ascertain accurately. Often, the case is not faulty senses per se, but unique senses. Color is a good example of this. Since everyone's eyes are different, we don't really see colors in exactly the same way. A shade of green could be lighter or darker than how another person perceives it. The difference is not very large, but it exists nonetheless. The objects around us may in fact exist, but they exist differently due to differing perceptions. Several factors influence our perception other than our senses, including where we see the object, how long we see the object, and our prior knowledge of the object. Accordingly, no single, universal definition can be given to anything because we all see the world through a different lens.