Unattainable ideal types function as measuring sticks for real cases.

Evidence

In this book I should like to reserve the term “democracy” for a political system one of the characteristics of which is the quality of being completely or almost completely responsive to all its citizens. Whether such a system actually exists, has existed, or can exist need not concern us for the moment. Surely one can conceive a hypothetical system of this kind; such a conception has served as an ideal, or part of an ideal, for many people. As a hypothetical system, one end of a scale, or a limiting state of affairs, it can (like a perfect vacuum) serve as the basis for estimating the degree to which various systems appropriate this theoretical limit. — Gary Goertz, Social Science Concepts, 559

Categorization

• DEFINE: Shows how an ideal type is defined as a limiting case rather than an existing entity.
• SEED: An essay on the perfect-vacuum analogy: how the sciences use unachievable limits (absolute zero, ideal gas, frictionless plane) as analytic baselines.