The topic of this book is the subject of an ancient debate – whether thought is independent of language, or whether our thinking, on the contrary, necessarily requires or involves natural language. I shall be arguing for a version of the latter thesis. My view is that much of human conscious thinking is, necessarily (given the way in which human cognition is structured), conducted in the medium of natural-language sentences.

I do not make any claim to demonstrate the truth of this view beyond all reasonable doubt. For the arguments that I provide in its support are broadly empirical ones, involving inferences to the best explanation of a range of phenomena. They are therefore vulnerable to counter-attack from those who can provide further recalcitrant data, and may reasonably be rejected by anyone who can provide a better explanation of the phenomena in question. I do hope to show, however, that the case for the independence of thought from language is by no means as clear-cut as many philosophers and cognitive scientists have assumed. And I therefore hope to provide encouragement for further work to be conducted in the alternative, language-involving, paradigm. Roughly speaking, the overall message of the book has the form, ‘Hey! Let's have a look over here! There's a view which hasn't been taken as seriously as it should be lately.’