"Trying to understand the brain's abilities leads to philosophical difliculties. Penrose (1994) argues that the task is sterile and that science, including neural networks, has not yet advanced to the stage where it can explain conscious thought. At the other extreme there are philosophers such as Fodor (1975) who believed that thought has language-like properties and can be analysed in the same logical way as one can anlayse the structure of language."