Imagine: you've been the victim of a horrific terror attack. The flashbacks will keep you up nights for the rest of your life. Doctors can give you a drug to blur the memories, but the government insists that you not take it since information you may be able recall could help fight terrorism.
Imagine: you've been in a terrible accident. The experience will cause long-lasting psychological trauma unless you take a drug that causes amnesia - but you will also forget details that could lead to the conviction of the person responsible. You're conscious, but in great pain; you have ten minutes to decide before you go into surgery. What will you do?
A New Scientist interview (24 April 2004, p46) with Richard Glen Boire, co-founder of the Center for Cognitive Liberty and Ethics in Davis, California, explores what the freedom of thought means once drugs can influence mental processes.
The examples above are not completely fanciful; people who take the beta blocker propranolol within six hours or so of a traumatic event have a reduced recall of that event.
Since we construct our sense of self moment by moment through recall, such drugs change who we are. To my mind, the changes are much more profound than cosmetic surgery, performance enhancers or even mood altering chemicals like Ritalin.