If there were a Gedankenexperiment about Man's constitution - What would it be?

Courtesy of Wikipedia-Gedanken

A thought experiment, sometimes called a gedankenexperiment in German, is a proposal for an experiment that would test or illuminate a hypothesis or theory.[1]
Given the structure of the proposed experiment, it may or may not be possible to actually perform the experiment and, in the case that it is possible for the experiment to be performed, there may be no intention of any kind to actually perform the experiment in question. The common goal of a thought experiment is to explore the potential consequences of the principle in question.

Famous examples of thought experiments include Schrödinger's cat (pictured above) , illustrating quantum indeterminacy through the manipulation of a perfectly sealed environment and a tiny bit of radioactive substance, and Maxwell's demon, in which a supernatural being is instructed to attempt to violate the second law of thermodynamics.
Schrödinger wrote:

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in aGeiger counter, there is a tiny bit of radioactive substance, so small that perhaps in the course of the hour, one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges, and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.

It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naively accepting as valid a "blurred model" for representing reality. In itself, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.^[3]

The above text is a translation of two paragraphs from a much larger original article that appeared in the German magazine Naturwissenschaften ("Natural Sciences") in 1935.^[4]

Schrödinger's famous thought experiment poses the question, when does a quantum system stop existing as a mixture of states and become one or the other?

Each alternative seemed absurd to Albert Einstein, who was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:

You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gunpowder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.^[5]

Thought experimentation in general

In its broadest usage, thought experimentation is the process of employing imaginary situations to help us understand the way things really are (or, in the case of Herman Kahn’s "scenarios", understand something about something in the future). The understanding comes through reflection upon this imaginary situation. Thought experimentation is a priori, rather than an empirical process, in that the experiments are conducted within the imagination (i.e., Brown’s (1993) "laboratory of the mind"), and never in fact.

Thought experiments, which are well-structured, well-defined hypothetical questions that employ subjunctive reasoning (irrealis moods) -- "What might happen (or, what might have happened) if . . . " -- have been used to pose questions in philosophy at least since Greek antiquity, some pre-dating Socrates (see Rescher). In physics and other sciences many famous thought experiments date from the 19th and especially the 20th Century, but examples can be found at least as early as Galileo.