  This paper proposes that two distinct types of structures are present in the
brain: Symbolic Knowledge Structures (SKSs), used for formal symbolic
reasoning, and Intuitive Knowledge Structures (IKSs), used for drawing informal
associations. The paper contains ideas for modeling and analyzing these
structures in an algorithmic style based on Spiking Neural Networks, following
the paradigm used in earlier work by Lynch, Musco, Parter, and co-workers. The
paper also contains two examples of use of these structures, involving counting
through a memorized sequence, and understanding simple stylized sentences.
  The ideas presented here are preliminary and speculative, and do not (yet)
comprise a complete, coherent, algorithmic theory. I hope that posting this
preliminary version will help the ideas to evolve into such a theory.
