>> The author really is incorrect to claim temperature is not a clearly understood concept

Temperature is a very inexact model of the dynamics of a system. It does not tell you anything about the energy of any individual atom. It's an aggregate number.

Thermodynamics was an eye opening course for me. Its impressive how much real engineering can be done with lumped parameter models. The author wants to convey the limitations of that approach.

The limitations of that approach don't line up with the example. Someone running a fever is running a fever because of an immune response to illness a lot of the time, which is an aggregate response. The body has trillions of cells, in the case of temperature you don't need a reading of each one. Researchers sometimes do, and medical testing of methods, drugs, or devices is a lot more scrutinized before doctors ever get access.

Yeah this guy gets it! Thank you :)

Yeah while you are correct I am not talking about that specific additive. I am talking about a gaseous system of atoms and how temperature is related in a statistical manner rather then being identified as an individual process. Maybe it cannot be identified individually. That lack of individual identification or proof against the ability of individual identification is enough to say that science in its broadest terms is vague