# Knowing How You Know/Height of the Eiffel Tower

Can the height of the Eiffel Tower be known? How might it be determined? You might look up the height in a reference such as Wikipedia, or search for other sources and find these answers:
| Reference | Reported Height |
| Wikipedia — Eiffel Tower Entry | Architectural:300 m (984 ft) Tip:324 m (1,063 ft) Top floor:276 m (906 ft) |
| The Telegraph — Travel — When did the Eiffel Tower open to the public? | It is 324 meters tall (including antennas) |
| History.com — 10 Things You May Not Know About the Eiffel Tower | 986 feet |
| My friend who saw it. | “Really tall!” |
Someone else might visit the tower and measure its height directly by ascending to the top, dropping a string to the bottom and measuring the length of string. Yet another person might use various surveying techniques involving a transit or triangulation or laser measuring devices. Techniques using GPS devices or changes in barometric pressure might provide other measurements. Historic and recent engineering drawings and plans could be consulted.
If these various techniques for measuring the height give different results, how do we best interpret these discrepancies? Perhaps the height is unknowable, or is a matter of opinion or belief or just a feeling. It is more likely, however, that the Eiffel Tower does have a height, the actual height is knowable to the limits of our measurement accuracy, and the variations in the heights reported reflect errors in the various techniques used for each measurement.
The principle of consilience assures us that the tower does have a height and that increasingly accurate efforts to measure the height will converge toward the actual height. The principle of consilience is at the foundation of every coherent theory of knowledge. When two different approaches to measuring the same length arrive at different results, there is an opportunity to learn about measurement techniques by comparing the measurements and investigating to resolve the discrepancies. The investigators might ask: Was the same definition of height used in each case? Were the same units of measurement used? Were the measuring instruments accurately calibrated? Was the accuracy of each measurement device used known? Could the height have varied as a result of thermal expansion as the temperature varied throughout the day or some other dynamic effect?
Facts provide common ground. We all live on the same planet within the same known universe. Reality provides us a universal reference standard. Careful examination of our world as it actually is can bring us toward agreement about what is true about our world. This shared knowledge about how our world is can form a substantial common basis for discussing what could be and even what ought to be. Reality is our common ground. We can progress together by converging toward reality.
As a result of consilience, reliable epistemologies—ways of knowing—converge on matters of fact. A lack of convergence casts doubt on the reliability of the methods used for establishing facts. Pursuing such discrepancies can lead to important insights about the reliability of our methods. Agreeing to disagree on matters of fact is a decision to accept complacency and incoherence.
The Eiffel Tower has a height. Conscientious efforts to determine that height will result in a series of increasingly accurate estimates converging toward the actual height.
When two people are disagreeing about a factual claim it is time to stop arguing and start researching. Do not debate matters of fact, instead investigate and research more deeply to determine the facts. Understand the boundaries of tolerance. Do not tolerate matters of fact being characterized as opinions, beliefs, feelings, or culturally relative. Facts are stubborn, learn from them.