Sources of Knowledge
Okay, so some knowledge requires experience and some doesn’t. Here are a few more specific sources of knowledge that fit into the two categories of a priori and a posteriori:
Perception
Memory
Consciousness
Reason
Testimony
Perception
We learn about the world through our sense experience. I know I’m in this room because I can see, smell, hear, taste, and feel the world around me. Sense experience gives me a direct impression of the world. This is a posteriori knowledge because it requires my sense experience to gain this knowledge.
Memory
Memory can be a source of knowledge as well. I’m not currently in my office, so my sense experience cannot be my primary source of knowledge of the classroom; however, I remember what it felt like to be in my office. This type of knowledge is not quite as secure as immediate sense perception, but it can be reliable too.
Consciousness
Introspection can be a way of gaining knowledge about oneself. I can know how I feel by looking inward. This is sometimes considered an inner perception, similar to outward perception of the room or objects. However introspection is not a knowledge that can be confirmed by others, only yourself.
Reason
A priori truths many times come from the use of reason. Human beings are rational creatures. Our minds are governed by certain rules of thought. For example, when I see two trees, I can perceive that one is taller than the others, but that perception imposes the use of reason, if one is taller than the other then logically one is shorter than the other. Mathematical truths are also found through the use of reason (e.g., 1 +1=2). We can also apply this power of reason to analyze concepts (e.g., triangles have three sides) or even linguistic truths (e.g., a bachelor is an unmarried man).
Testimony
We also learn about the world through the knowledge gained from others. I did not personally see Thomas Jefferson sign the Declaration of Independence, but I know he did because other people witnessed this signature and wrote down what they saw. I also don’t know that water is made of H2O personally, I have never done the chemical experiments necessary to gain this information for myself through perception. I take the word of experts who have done this for themselves. Much of our knowledge is from testimony, but also, testimony can be unreliable because other people can be unreliable.
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Of the five sources of knowledge, 1) which do you think is the most reliable? 2) which is the most useful? and 3) which is the most likely to mislead you? (explain why you believe this for each)
