However, is that "belief" well grounded? How do we know that our memories really do concern events that were experienced by *us*? What if a scientist made a transplant of a memory from one brain to another? Is that scenario possible? That scientist would transplant from person A to person B the memory of walking through London, even though person B never visited London in his life. Although he never visited London in his life, he would remember walking through London because person A walked through London in the past and acquired a memory of that event. Is this scenario possible? Can one's memories be the result of a transplant?
I think skeptical scenarios like the malignant genius or the brain in a vat one are incoherent. But what about this one? What to think of it from a thomistic point of view?