The Replicants in BLADERUNNER tried to fabricate the past by collecting photographs of some distant past. They did not have actual memories of those moments captured in photographs. Then, why do they need to have these external artifacts? If I have a photograph taken 20 years ago, and if I have no recollection of having that particular moment depicted in it, then what does that prove? Did I lose the memory of the event? Or did someone fabricate the photograph using Photoshop? If you can believe what you see in a photograph rather than you remember, then are you a Replicant?