Knowledge has been a word and concept that has been discussed for centuries. Since the first Greek philosophers, what it means to know has been understood differently by many people. The Latin word for knowledge is conscientia1, which also means conscience and consciousness. With this, we can start to understand how knowledge was originally understood and used. If it's similar to consciousness, it must mean that knowledge is something only within ourselves and can only exist there, just like the state of being conscious is the awareness of one's own existence, sensations, thoughts, etc.3 That means anything outside our mind we can't have any knowledge of; anything of the physical world. This is the problem being addressed now: the very common misuse of the verb to know. We can make very simple claims such as "I know this table is brown" and still be wrong. Our senses could be skewing all outside information to a great extent, as suggested by the rationalist group of thought in philosophy. Due to this, we won't ever have true knowledge of the colour of the table. Even the air as a medium through which we see the table could be distorting many facts about it, leaving us even further from the truth. The definition of knowledge says that it's the apprehension of fact or truth with the mind; clear and certain perception of fact or truth4. No matter how clear or certain your perception is, perception is still the act of apprehending by means of the senses or of the mind2 and we know that we can't fully trust our senses.
There is also a notion that knowledge is the highest level of thought. It is a hierarchy of three thought levels: opinion, belief and knowledge. Opinion is at the bottom, having the least general importance. Opinion is just something personal and is different for everyone; it can be wrong or right or even neither. Belief follows opinion. Belief is a much stronger opinion, backed up by more evidence and reasoning and doesn't change as easily. I understand that belief is the closest we can come to true knowledge. True knowledge is something outside our grasp and outside our reality. I also want to introduce Plato's Ideal World. To describe it very briefly, it is a theory that states that there is an ideal world in all our minds where we are able to understand concepts such as a perfect circle. When we draw a circle, we try to imitate this perfect circle from our mind but it will always be impossible. I understand that true knowledge resides in this ideal world and only there. Therefore I want to emphasize the importance of using phrases such as "I strongly believe" versus "I know" in almost any case. This way, you will be more accurate with your display of your knowledge.
1. "Latin Word for Knowledge >> Conscientia." Latin Word List. http://www.latinwordlist.com/latin-word-for/latin-word-for-knowledge-13125180.htm (accessed November 13, 2012).
2. "Perception." Dictionary.com. http://dictionary.reference.com/browse/perception?s=t (accessed November 13, 2012).
3. "conscious." Dictionary.com. http://dictionary.reference.com/browse/conscious?s=t (accessed November 13, 2012).
4. "knowledge, n.." Oxford English Dictionary. http://oed.com/view/Entry/104170?rskey=IIiFAM&result=1#eid (accessed November 13, 2012).