Philosophy of Being and Knowledge

Logic (Philosophy of Thought)

Classification of Concepts

Concepts vary widely. In logic, there is an established tradition of classifying concepts according to various criteria:

• By Content:

✵ Simple and Complex: A simple concept is one expressed by a single word (e.g., human, air, life); a complex concept is expressed by two or more meaningful words (e.g., perpetual motion machine, first president of Ukraine, red table).

✵ Concrete and Abstract: Concrete concepts involve characteristics associated with their bearers (e.g., kind person, beautiful car); abstract concepts involve characteristics without their bearers (e.g., kindness, beauty, strength).

✵ Positive and Negative: A positive concept denotes the presence of certain attributes in an object (e.g., person, thing, sentence); a negative concept denotes the absence of certain attributes (e.g., nonhuman, irresponsible).

✵ Relative and Absolute: Relative concepts are understood only in relation to another concept (e.g., son, parents, tomorrow); absolute concepts denote objects whose existence is logically independent of other objects (e.g., human).

• By Extension:

✵ Empty and Non-Empty: Empty concepts have zero extension, meaning they encompass objects that do not exist and never have (e.g., perpetual motion machine, absolutely black body); non-empty concepts involve objects that exist or have existed (e.g., water, human, table).

✵ Singular and General: Singular concepts refer to only one object (e.g., the Sun, the longest river on Earth); general concepts encompass many objects, or all individuals of a type (e.g., human, writer, planet).

✵ Collective and Non-Collective: Collective concepts refer to multiple objects considered together as forming a new reality (e.g., constellation, orchestra, society); non-collective concepts refer to individual objects (e.g., star, musician).