Describe the theory of knowledge called skepticism

Describe the theory of knowledge called skepticism. Consider the skeptic’s charge that we can never be confident about the reliability of our normal sources of knowledge (perceptions, memory, introspection, and reasoning.) Describe why and how, for each of the 4 sources mentioned, the source is unreliable. Use examples to show your understanding.

If a source of knowledge is unreliable, it means these sources can trick us into believing falsehoods. Does it follow from the fact that we are sometimes mistaken when we rely on these sources that we are always mistaken? In other words, once we admit is possible that we are mistaken, does that mean that we need to admit that we might never be correct? How would you respond to the skeptic?