I WONDER very much whether anyone really noticed the title of this address, Prerogatives of Systems; or whether, having noticed, he was at all concerned. Perhaps he put it down to my ignorance—or his own. For a prerogative is an entitlement to priority. How then can systems have prerogatives? Surely it is only living beings who have entitlements. And if we put the word prerogative in its most familiar context, these living beings are ourselves. It is the human prerogative that counts.