Comment 15 by QuestioningKat

Does it interact with matter...at all?

If an idea doesn't have anything to do with matter, I think anyone trying to prove it would be in trouble, don't you? Even mathematics and logic are about matter sooner or later.

Ideas do not make copies spontaneously, human interaction is necessary.

That's my point. If a thing cannot make copies of itself, it doesn't fulfil the criteria needed for a replicator, though it can mimic one superficially just as a leaf insect can mimic a leaf. The copying mechanism, however, might be a benefit to genes if their success depended on relatives or helpful partners holding common ideas. On another thread of mine (which I think you've seen), I suggested some reasons why people sharing the identical ideas could be adaptive: for instance, that it makes it easier to cooperate or to bond (by reducing mutual misunderstandings - after all, you see the world roughly as they do), because of a social contest in which one advertises one's mental prowess by feats of memory for trivia and cultural mores etc.

If an idea does not have any tangible, literal substance and exists purely in an abstract state, it can never literally copy itself. Any transfer from one person to another is still in this abstract form which is communicated from one person to another. It can be communicated through any of our senses, intellect, emotions.... We can show a physical object and people can literally copy this, yet the underlying concept of the object is what is being examined. This process is not literal and searching for direct physical evidence of one idea replicating seems impossible. We can examine the results of physical manifestation, but not the actual action/idea.

But this dualism of ideas and physical matter isn't really a dichotomy. My knowledge of football, for instance, doesn't sit apart from the physical technicalities of the sport, actual games I've witnessed, and the workings of one's own mind. I won't go into depth on it here, but in short appealing to an abstract realm like a Platonic cave and claiming it cannot be tested by matter is a cop-out because memetics neither requires it nor suggested it. It's moving the goalposts after I've done my critique.

I do agree that lineages of cultural ideas do look convincing, but I explained above how I think this lineage actually works, and it doesn't need replication.