Linguistic philosophers have long held that thinking requires words; anyone without language, including animals, is incapable of concepts or thoughts—and by extension, of planning ahead and recalling the past. Mary Midgley disagrees. In Animals and Why They Matter, she wrote:
I think it is clear that linguistic philosophers have often overstated the case for the dependence of intelligence [and understanding] on language in a way which their arguments do not justify and indeed do not require. Thus, for instance, Max Black, having said that man is the only animal to use symbols, goes on to add that he is 'the only animal that can truly understand and misunderstand. Similarly Stuart Hampshire writes, 'It would be senseless to attribute to an animal a memory that distinguished the order of events in the past, and it would be senseless to attribute to it an expectation of an order of events in the future. It does not have the concepts of order, or any concepts at all.' Plainly neither Black nor Hampshire is controverting—or is even interested in—the very large literature of careful discussion by zoologists and psychologists about the different kinds of understanding and conceptual grasp which different sorts of animals actually display. This work would not impress them. Their point is one of definition. They are not prepared to count as concept or as understanding anything which does not involve speech.
An interesting article by Professor Ray Monk, an expert on Ludwig Wittgenstein's life and work, sheds new light on what the great linguistic philosopher thought of the matter himself (h/t 3QD). I was also happy to see that this article supports my own intuitions about animal minds and the ideas I expressed in an article I wrote earlier this year, The Inner Lives of Animals, and in its comments section.
“Thinking in pictures,” Sigmund Freud once wrote, “stands nearer to unconscious processes than does thinking in words, and is unquestionably older than the latter both ontogenetically and phylogenetically.” There is, in other words, something primordial, something foundational, about thinking visually. Such a view is anathema to many philosophers, a good many of whom believe that all thought is propositional, that to think is to use words. For some of the most distinguished philosophers in history, thinking and verbalising were practically the same thing. Bertrand Russell sometimes to his great frustration, was hopeless at visualising and was more or less indifferent to the visual arts. His mental life seemed almost entirely made up of words rather than images. When his friend Rupert Crawshay-Williams once gave him an intelligence test that involved matching increasingly complicated geometrical shapes, Russell did extremely well up to a certain point and then exceptionally badly after that. “What happened?” Crawshay-Williams asked. “I hadn’t got any names for the shapes,” Russell replied.
In this, as in many other respects, Ludwig Wittgenstein was Russell’s opposite. For Wittgenstein, to think, to understand, was first and foremost to picture. In conversation with his friends, he several times referred to himself as a “disciple” or “follower” of Freud and many people since have been extremely puzzled what he might have meant by this. I think Freud’s remark quoted above might provide the key here, that it might have something to do with the emphasis one finds in Freud on the primordiality of “thinking in pictures”.