Professor Spolsky sets out his theory in the form of a preference model, or
series of typical and categorical rules or conditions. In this way he is able
to account for both differences between individual language learners, and between
different kinds of learning Ц for example formal and informal learning,
and learning for general and special purposes. The model emphasises the need
to be precise and clear on the nature of the goals and outcomes of learning,
and to recognise the complexity of the concept 'knowing a second language'.