A great many abstract concepts can be put into words (which are, to generalize, abstract symbols) - that is one of the great powers of human language. I wanted to ask what ideas cannot be so expressed, but of course there is a problem...
There may be candidates in qualia, the subjective experiences that tend to tie the philosophy of mind in knots, and which, being subjective, cannot be communicated precisely in language (can you tell a blind person what it is like to see red, such that they can learn it from your words?) In these cases, however, our internal monologue could refer to them indexically ("seeing red is like that", where that picks out an aggregation of memories.)
Bizzarre as this may seem to you, I can assure you that it feels very natural, easy and straightforward, though it might be something of an illusion, merely the way we explain thinking to ourselves when we pay attention to doing it (see my other post.)
There may be candidates in qualia, the subjective experiences that tend to tie the philosophy of mind in knots, and which, being subjective, cannot be communicated precisely in language (can you tell a blind person what it is like to see red, such that they can learn it from your words?) In these cases, however, our internal monologue could refer to them indexically ("seeing red is like that", where that picks out an aggregation of memories.)
Bizzarre as this may seem to you, I can assure you that it feels very natural, easy and straightforward, though it might be something of an illusion, merely the way we explain thinking to ourselves when we pay attention to doing it (see my other post.)