how can you practice Aikido, if you don't acknowledge the experiential reality of ki? Doesn't matter if ki has no scientific reality or if you prefer to use a different word of set of words to describe it, 'no ki, no aikido' still applies.
While I understand Chris's point, I think it misses the point that the root word, in and of itself, provides contextual richness to the compound. Without the meaning assigned by the root modifier, the compound loses it's whole meaning.
As an example, 合力 hé lì is a compound meaning "cooperate". What does it mean to "cooperate" if there was no such thing/concept as "union" or "strength"?
Mars need not have been a concrete entity. What Mars represented/embodied (abstract entity) is what gives us the word martial. In the same vein, what ki represents/embodies is what gives aiki meaning. If there is no such thing (concrete or abstract) as ki, what is the meaning of aiki? Or for that matter, what is aiki, if there is no such thing as ai?