The definition must contain the essence of what is being defined. The essence, in our example, is really what makes a planet a planet. In order to test for this you must make sure the definition is neither too broad nor to narrow. For example, if I say that a planet is an object in space that orbits a star it sounds like a decent definition. However, this definition includes more than just planets. Many other things, such as moons, asteroids, and random debris all commonly orbit stars. These items are not planets so the definition would be deemed “too broad.” On the other end of the spectrum, we can try to be more specific and say that a planet is a large, solid, object in space with its own moon or moons that orbits a star. This seems like it covers the bases of a planet but its leaving out too much. The word “solid” itself eliminates too many planets such as the gas giants in our own solar system. According to this definition, Jupiter, Neptune, Saturn, and Uranus are all left out because they are made of gas and therefore not “solid.” This goes to show how difficult the second rule can
The definition must contain the essence of what is being defined. The essence, in our example, is really what makes a planet a planet. In order to test for this you must make sure the definition is neither too broad nor to narrow. For example, if I say that a planet is an object in space that orbits a star it sounds like a decent definition. However, this definition includes more than just planets. Many other things, such as moons, asteroids, and random debris all commonly orbit stars. These items are not planets so the definition would be deemed “too broad.” On the other end of the spectrum, we can try to be more specific and say that a planet is a large, solid, object in space with its own moon or moons that orbits a star. This seems like it covers the bases of a planet but its leaving out too much. The word “solid” itself eliminates too many planets such as the gas giants in our own solar system. According to this definition, Jupiter, Neptune, Saturn, and Uranus are all left out because they are made of gas and therefore not “solid.” This goes to show how difficult the second rule can