Green Martians and Blue Martians have one thing in common: They both derive a tremendous amount of utility from tickling humans behind the ears, using their soft, feathery tentacles.  In fact, the utility that they derive from this is so intense that most scientists believe at some time in the recent evolutionary past, there must have been a large selection pressure directed at ensuring that Martians were motivated to tickle humans.

There are numerous differences between Green and Blue Martians. One of those differences is that whereas the feathery tentacles of Green Martians contain stinging hairs similar to nettles, the analogous anatomic part of the Blue Martian contains a safe drug with an euphoric effect. Therefore, humans who are tickled by green martians experience a moderate stinging pain, whereas those who are tickled by blue martians experience mild to moderate pleasure.

Human ethicists have long struggled to come up with a coherent ethical theory that determines whether tickling humans is morally acceptable.  Some have suggested that tickling humans behind the ear is ethically permissible if and only if you are a blue martian.  However, many other thinkers are worried that this line of thinking results in an unjust world, where the ethics of an act is determined by characteristics of the Martian that they cannot be held responsible for.

However, human ethicists are not very familiar with Martian physiology, and the situation is actually even more complicated than they suspect. In fact, all Martians are born Green.  They can shed their green shell and become blue Martians only after they have perfected the art of tickling humans with their feathery tentacles. All Martians aspire to one day become blue, but the amount of practicing it takes to reach perfection is highly variable - some martians reach perfection at their first attempt, whereas others keep trying their whole life without making any discernible progress. Therefore, if the ethical code says that green martians are prohibited from tickling humans, ethical Martians will be unable to reach their full potential in life, and will be stuck as Green Martians forever. Under this ethical code, only unethical Martians will be able to metamorphose.  

Making the situation even more complicated, is the fact that a group of recently metamorphosed Blue Martians are vocally spreading information on the internet about tickling techniques. These techniques are sometimes effective, but if used imperfectly they increase the sting of the stinging hairs fourfold. Importantly, it seems that part of the reason some young Green Martians are naturally better ticklers and therefore metamorphose earlier, is that they intuitively understand these techniques, and are able to apply them without increasing the sting of their tentacles.  Moreover,  while the tickling technique has empirical support, the theory behind it relies heavily on speculation about human evolutionary history that may not be true, and which is offensive to humans. 

This raises a number of additional ethical questions: Is it unethical for a Green Martian to attempt to metamorphose?  Does this depend on whether they believe themselves to be fast or slow learners? Should only the small subset of Martians who intuitively understand the tickling techniques be allowed to use them? Is spreading explicit information about the techniques unethical? 

 (Note : This parable is obviously an allegory for something.   Discussing whether the allegory is valid is interesting, but will lead to mindkill.   I would prefer if the discussion could stay focused on the Martians, so that we can discuss the ethics of a hypothetical scenario that may not be relevant in real life.  I am genuinely confused about the ethics of this, and I think this can lead to an interesting question regardless of whether it is applicable to humans)