Units of Knowledge
As mentioned before, there are units of knowledge that make up the components that work together to process information and create a thought. There are three basic units of knowledge: concepts, prototypes, and schemata.
The first unit of knowledge is the concept. This is basically a category that groups together items with similar characteristics or properties. These are the building blocks that are used to create the foundation of thought. Concepts can represent objects, abstract ideas, relationships, or activities. For instance, dog is a concept, but so are love, exercise, marriage, and weather. Each concept has a list of characteristics that define it. For example, dog would have a list that included bark, tail, fur, and four legs. A German shepherd, poodle, Chihuahua, mastiff, and rottweiler are all examples of this concept.
This isn't to say that all examples must have the exact same characteristics. For instance, not all dogs bark and not all birds fly, but those nonbarking dogs are still examples of the dog concept and those nonflying birds are still examples of the bird concept. All examples of the concept will share a “family resemblance.”
Taking the idea of a concept one step further, you come to prototypes. A prototype is basically the most recognizable example of a concept and is therefore the representative of that concept. When your mind is trying to decide where to categorize an impression, it compares that impression with the prototype of a concept. If the impression has similar characteristics to that prototype, it will become an example of that particular concept. For example, your prototype of a chair is likely a piece of furniture used for sitting that has four legs, an upright, straight back, and a square or rectangular seat. When you came across a highchair for the first time, your brain processed the impression, comparing it to the prototype of the chair. Once it determined that the highchair had characteristics similar to that prototype, it was filed away as an example of the concept chair.
Concepts are building blocks, so your brain uses them to build. Concepts are put together to create propositions, which are units of meaning expressing a single idea. Come up with a sentence, any sentence. This is a proposition. Propositions that are related are linked and create a network of knowledge and information that makes up a schema. A schema is basically a mental model of what you expect from a particular encounter. These schemata are built using your experience and concepts and allow you to have certain expectations when you encounter ideas, beliefs, situations, or people in your environment. You can create schemata about anything from a jog in the park to a particular religion to a race of people.
So what happens when you encounter information that does not conform to your existing schemata? While most people are easily able to absorb and incorporate new information into their existing worldview, conflicting information can cause a few different things to happen. In some cases, a person might simply choose to ignore a piece of new information that disagrees with his or her existing schema. Generally, this happens on an unconscious level and the person is not even aware that the information has been ignored or forgotten. However, when conflicting information simply cannot be ignored, a schema-changing process known as assimilation may take place. For example, imagine a child with an existing schema for cats. According to this child's schema, all cats have four legs, a long tail, and fur. So what happens when the child encounters a three-legged, hairless, bobtailed cat? The child would probably assimilate this new information into the existing schema for cats, but she might even form a new schema for this particular variety of cat.
Heuristics are a type of mental shortcut that people frequently use to reason and solve problems. A heuristic is basically a rule of thumb that is used to guide your actions toward producing the best possible solution, but this does not mean that the best possible solution will be reached; heuristics are just guidelines and cannot guarantee an outcome.
For instance, those who play chess know that a good rule of thumb is to build up a good defense to protect your king. When you take action to utilize this strategy, you are applying a heuristic. Again, winning the game is not guaranteed from using this heuristic, but it certainly increases your chances! Or perhaps you suspect your significant other of being dishonest with you. While you may not have all the premises to work with, you can use a heuristic to help you solve the mystery: trust a man's actions before his words. Can you think of any other heuristics you often use to reach a solution to informal reasoning problems?