Philosophy of Being and Knowledge

Logic (Philosophy of Thought)

Relationships Between Concepts

Every pair of concepts exists in a specific relationship with each other. Researchers of human thought have successfully classified all possible types of relationships between concepts.

• Incommensurable Concepts: When two concepts share no commonality whatsoever, they are termed incommensurable (e.g., joy and chair, electron and love).
• Commensurable Concepts: When two or more concepts can be compared, they are referred to as commensurable. For concepts to be commensurable, they must share a common generic characteristic of any order (e.g., table and wardrobe, man and woman, tree and grass). The relationships between commensurable concepts can be of two types:

✵ Compatible Concepts: These are concepts whose extensions overlap either completely or partially (e.g., student and athlete). Compatible concepts, in turn, fall into three categories:

• Identical Concepts: Concepts whose extensions entirely coincide (e.g., Kyiv and capital of Ukraine, Hebrew and official language of Israel).
• Overlapping Concepts: Concepts whose extensions partially overlap (e.g., student and athlete).
• Hierarchical Concepts: Concepts where the extension of one is entirely included within the extension of the other, while the extension of the latter only partially includes the extension of the former (e.g., notary and lawyer, textbook and book).

✵ Incompatible Concepts: These are concepts whose extensions do not overlap at all (e.g., man and woman, barley and wheat). Incompatible concepts are of two types:

• Neutral Coordinates: Concepts that express different types within a genus but are not opposites (e.g., lawyer and prosecutor).
• Antagonistic Coordinates: Concepts that are different types within a genus and mutually exclude each other, representing opposites. They are further divided into:
• Contrary Concepts: Antagonistic coordinates that constitute two polar types within a genus (e.g., black and white).
• Contradictory Concepts: Antagonistic coordinates that encompass two antithetical types within a genus, whose extensions exhaust the extension of the generic concept (e.g., white and non-white).