The Booker-prize winning novelist reflects on the times in his life when recollection and imagination have intertwined, and wonders whether we can ever rely on our brains to provide us with the truth

It sounds a simple business. “I changed my mind.” Subject, verb, object – a clear, clean action, without correcting or diminishing adjectives or adverbs. “No, I’m not doing that – I changed my mind” is usually an irrefutable statement. It implies the presence of strong arguments which can be provided if necessary. The economist John Maynard Keynes, charged with inconsistency, famously replied, “When the facts change, I change my mind.” So, he – and we – are happily and confidently in charge of this whole operation. The world may sadly incline to inconsistency, but not us.

And yet the phrase covers a great variety of mental activities, some seemingly rational and logical, others elemental and instinctive. There may be a simmering-away beneath the level of consciousness until the bursting realisation comes that, yes, you have changed your mind completely on this subject, that person, this theory, that worldview. The dadaist Francis Picabia once put it like this: “Our heads are round so that our thoughts can change direction.” And I think this feels as close to a true accounting of our mental processes as does Maynard Keynes’s statement.