On Thinking

The collection's central argument is that thinking is not a hidden inner act or a ghostly performance that accompanies overt behavior. Ryle develops the concept of 'adverbial verbs' to make this point: when someone does something 'thoughtfully' or 'hurriedly,' they are not performing two acts—the act and a separate mental act—but one act under a certain qualification. Thinking is a way of doing things, not a separate thing done alongside them . What On Thinking rejects is the 'Duplicationist' picture, which Ryle sees as common to both Cartesianism and some forms of behaviorism: the assumption that if thinking is real, it must be a distinct inner occurrence, whether a mental soliloquy or a hidden computation. Ryle's target is the very grammar that makes the question 'what is thinking?' seem to require an inner object.

The adverbial analysis is Ryle's tool for dissolving the apparent mystery of thinking. His example is a soldier lowering his arms on command: the soldier does not perform two actions—lowering his arms and obeying—but one action under the description 'obeying' . Similarly, thinking is not a separate inner performance but a qualification of what one is doing. Ryle extends this to 'thinking' itself: one can think while writing, while walking, while speaking, and the thinking is not an additional act but a mode of the activity. The analysis is meant to block the Duplicationist temptation, which posits an inner mental replica of the outer behavior. The later essays refine this account, distinguishing cases where 'thinking' functions adverbially from cases where it seems to stand alone, as in Rodin's Thinker.

On Thinking is explicitly a response to a gap in The Concept of Mind. Ryle's earlier book was widely criticized for its treatment of thinking—or rather, its failure to treat it. The Concept of Mind focused on overt behavior and dispositions, but critics insisted that the activity of 'just sitting and thinking,' exemplified by Rodin's statue, got short shrift . Ryle acknowledged the gap and spent the last decade of his life returning to the problem. On Thinking collects the results. The relationship is therefore one of extension and repair: Ryle does not abandon the anti-Cartesian project of The Concept of Mind, but he attempts to give a more adequate account of the activity that the earlier book had left largely unanalyzed.

Ryle died in 1976 while preparing a book on thinking. The work remained a project, and three years later Konstantin Kolenda published a collection of essays Ryle had written on the topic, with a preface by G. J. Warnock . The first three essays—'Adverbial Verbs and Verbs of Thinking,' 'Thought and Soliloquy,' and 'Thought and Imagination'—were previously unpublished and appear to have been intended for the projected book. The remaining six were published in journals and collections between 1972 and 1976 . This posthumous status matters: the collection is not a unified treatise but an unordered mixture of essays, and reviewers noted repetition and unevenness. One reviewer described it as 'an unordered mixture of very cautious and begrudging concessions to the opposition, lambastings of strawmen, and canny observations' that 'could not be called complete or successful' . It is valued as a document of Ryle's late thinking rather than as a finished work.

The essays 'Thought and Imagination' and 'Improvisation' extend the analysis beyond the adverbial model. Ryle attempts to dismantle two common assumptions: that thinking and imagination are diametrically opposed, and that imagination is a species of thinking. He distinguishes within thinking between imaginative and non-imaginative varieties, and he analyzes improvisation as a form of thinking-in-action that is neither mere habit nor explicit calculation. A reviewer noted that Ryle's description of creative thinking and problem-solving in 'Thought and Imagination' is 'excellent and typically graphic,' valuable in its own right, though put to dubious use against the computer model of mind . The essay anticipates distinctions between algorithmic and heuristic processing, even as Ryle resists the idea that computers can think.