Knowledge

What does it mean to truly know something?

Knowledge is a complex concept involving awareness, familiarity, or practical skill. It can be viewed as a cognitive success or an epistemic contact with reality. Many scholars focus on propositional knowledge, which is the belief in specific facts. For example, one might say, "I know that Dave is at home." However, knowledge is not limited to facts alone. It also includes practical competence, known as knowledge-how, such as knowing how to swim. There is also knowledge by acquaintance, which is a direct familiarity with a person or object through experience.

Knowledge can exist in different forms and scales. It is often seen as a state within an individual person. Yet, it can also be a characteristic of a group, called collective or social knowledge. Some social sciences treat knowledge as a broad phenomenon similar to culture. It can even be stored externally, such as the knowledge housed in a library or an expert system. While knowledge is closely related to intelligence, the two are distinct. Intelligence is the ability to process and apply information. In contrast, knowledge refers to the information and skills a person already possesses.

People acquire knowledge through several different mechanisms. Perception is a primary source, using the senses to learn about the external world. Introspection allows individuals to learn about their own internal mental states. Other sources include memory, rational intuition, inference, and testimony. Philosophers debate how these sources support one another. Foundationalists argue that some beliefs are basic and justify others without needing further support. Coherentists believe that a sufficient degree of coherence among all mental states is necessary. Meanwhile, infinitists suggest that knowledge requires an infinite chain of beliefs.

The study of knowledge is a major branch of philosophy called epistemology. This discipline investigates the nature of knowledge and its justification. Epistemologists ask how knowledge arises and what value it holds. They also explore the limits of what can be known. This includes discussing philosophical skepticism, which questions if knowledge is even possible. The history of the word "knowledge" traces back to the 12th-century Old English word *cnawan*. Ancient Greek thinkers used specific terms to distinguish different types of knowing. They used *epistēmē* for theoretical knowledge and *technē* for technical expertise. They also used *mētis* for strategic knowledge and *gnōsis* for personal intellectual knowledge.

A famous definition of knowledge is "justified true belief." This model requires three essential features: a belief, truth, and justification. Truth is vital because one cannot know something that is false. Being a belief is necessary because one cannot know something they do not believe. Justification is included to separate knowledge from lucky guesses or superstitions. For instance, a lucky guess about a coin flip is not knowledge. However, this definition faced challenges in the 20th century. An epistemologist named Edmund Gettier created thought experiments called Gettier cases. These cases show that a person can have a justified true belief that is still based on luck.

One Gettier example involves a person driving past many fake barn facades. If they stop in front of the only real barn by coincidence, they have a justified true belief. They believe they are in front of a barn, and it is true. However, they could not have told the difference between the real barn and the fakes. This suggests that their belief was a result of epistemic luck rather than true knowledge. Because of this, philosophers have proposed many new definitions. Some focus on reliability or cognitive virtues. Others suggest that knowledge must not depend on any false beliefs. Some even argue that beliefs must be infallible to count as knowledge.

Knowledge connects to many different academic and social fields. The sciences use the scientific method to acquire knowledge through repeatable experimentation and measurement. The anthropology of knowledge examines how different cultures acquire and communicate information. The sociology of knowledge looks at the social and historical circumstances where knowledge arises. Additionally, the history of knowledge tracks how various fields have evolved over time. Many religions also hold that humans should seek knowledge. Some faiths believe that God or the divine is the ultimate source of all knowledge.