One of Theo's guiding principles is that all knowledge should be open for inspection. By having all knowledge open to inspection to any rule Theo automatically gains meta-knowledge, i.e. it knows what is knows. Given this, it is easy for Theo to demonstrate meta-reasoning and self reflection.
Related principles that aids meta-reasoning are that all knowledge is uniformly stored and accessed and uniformly represented using a frame-based knowledge representation system.
Go to a discussion of this property for multiple architectures.