Definition of a Memetic Immune System

In any collection of memes, you will often find memes that help protect the memeplex from being attacked or destroyed or weakened. For example, when non-Arabic speaking non-Muslims learn what is in the Quran, Muslims will use something in the Islamic memeplex: That the Quran can only be understood in Arabic.

So unless someone reads the Quran in Arabic, anything they say can be discounted. This is an example of Islam's memetic immune system.

Read more about this in the book, Thought Contagion.