In possibly the most significant extension of the strange loop idea, Hofstadter contends that our brains are not limited to supporting one strange loop—although one, containing the individual’s “I,” will always be dominant. This means that it is possible for your brain to host a low-fidelity version of another person’s mind. When two people are very close, such as a couple who have known each other intimately for some time, Hofstadter argues that they in effect begin running rough copies of each other’s consciousness in their brains. While both partners retain their individuality, a gestalt entity eventually emerges. In this view of the mind, there is a literal meaning to the romantic notion of a “you, me, and us” in a close relationship.

And when someone dies, it is possible for rough copies of that person’s consciousness to live on in others. In an extraordinarily personal section of the book that markedly distinguishes I Am a Strange Loop from the more detached tone of Gödel, Escher, Bach, Hofstadter discusses this concept in the context of the sudden death of his own wife, Carol. When he brings his late wife strongly to mind—say, at an important moment for one of their children—he says his copy of her self-aware strange loop is activated.

In other words, Hofstadter is not just experiencing memories of her or imagining what she might have thought of the moment, but enabling a living echo of Carol herself to look through his eyes at their child. Although Hofstadter is aware that he thus risks being accused of wish fulfillment, this line of thinking does follow naturally from the rest of his argument.

If there’s a weakness in Hofstadter’s reasoning, it lies in his claims that the mind can be considered as an abstraction and that we can ignore the details of the brain or whatever other substrate the mind may be running on.

Hofstadter supports this claim with an analogy drawn from thermodynamics. He notes that the Ideal Gas Law can be studied purely by reference to a gas’s temperature and its pressure, concepts meaningless on the level of the individual molecules composing the gas. The precise microscopic arrangement of the molecules and the type of molecules they are do not matter.

But thermodynamic phenomena like the Ideal Gas Law operate in the domain of very large numbers of molecules indeed. Human brains, on the other hand, even with their 100 ­billion or so neurons, operate with 12 orders of magnitude fewer components than can be found in a whiff of gas. As many engineers have found out the hard way, you can use abstractions and ignore the substrate for most of the time, but every now and then you get caught badly when a handy assumption breaks down.

In recent years, for example, digital chip designers, who had long operated comfortably in the abstract world of gates and Boolean logic, have found themselves confronted by the full messiness of materials science and electromagnetic effects as they try to squeeze devices closer together. Even MEMS developers, although working with components vastly larger than atoms, find that familiar mechanical laws about how gears and levers move cannot always be trusted in the in-between world of the mesoscale.

Because it is precisely in this mesoscale world that our brains operate, this is where I have the most doubt about Hofstadter’s argument. Is there some fundamental element of our physical biology that is responsible for our consciousness? This is the thesis of a number of writers, notably the English mathematical physicist Roger Penrose. However, even if the thesis proves true, it would merely rule out the possibility of creating strange loops outside brains.

Hofstadter’s model for how self-aware beings can arise out of inanimate atoms still deserves to be taken seriously. I recommend the book both to those who have read his earlier work and to those who have not yet become acquainted with this great thinker.