If you’re caring for a person with dementia, what do you do if they demand to see their spouse, who in fact died long ago? If you resort to telling the person that their spouse has just gone to the shops and will be back soon, you’re not alone. “Therapeutic deception” is a time-saver for carers, and it can also be humane, a means of alleviating distress. But like all lying, it’s morally problematic.