Thinking is not mere computation—it is also cognition and contemplation, which inevitably lead to imagination. Imagination is how we elevate the real toward the ideal, and this requires a moral framework of what is ideal. Morality is predicated on consciousness and on having a self-conscious inner life rich enough to contemplate the question of what is ideal.
The famous aphorism often attributed to Einstein—"imagination is more important than knowledge"—is thus only interesting because it exposes the real question worth contemplating: not that of artificial intelligence but that of artificial imagination.
Of course, imagination is always "artificial" in the sense of being concerned with the un-real or trans-real—of transcending reality to envision alternatives to it—and this requires a capacity for holding uncertainty. But the algorithms that drive machine computation thrive on goal-oriented executions, in which there is no room for uncertainty—"if this, then that" is the antithesis of the imagination, which lives in the unanswered and often, vitally, unanswerable realm of "what if?" As Hannah Arendt once wrote, to lose our capacity for asking such unanswerable questions would be to "lose not only the ability to produce those thought-things that we call works of art but also the capacity to ask all the answerable questions upon which every civilization is founded."
Whether machines will ever be able to ask and sit with the unanswerable questions that define true thought is essentially a question of whether they'll ever evolve consciousness.
But, historically, our criteria for consciousness have been extremely limited by the solipsism of the human experience. As recently as the 17th century, René Descartes proclaimed "cogito ergo sum," implying that thinking is a uniquely human faculty, as is consciousness. He saw non-human animals as "automata"—moving machines, driven by instinct alone. And yet here we are today, with some of our most prominent scientists signing the Cambridge Declaration of Consciousness, stating that nonhuman animals do indeed possess consciousness and, with it, interior lives of varying degrees of complexity. Here we are, too, conducting experiments that demonstrate rats—rats—can display moral behavior to one another.
So will machines ever be moral, imaginative? It is likely that if and when they reach that point, theirs will be a consciousness that isn't beholden to human standards—their ideals will not be our ideals, but they will be ideals nonetheless. Whether or not we're able to recognize these processes as thinking will be determined by the limitations of human thought in understanding different—perhaps wildly, unimaginably different—modalities of thought itself.