Aikido is personal and universal
This is a silly thread (and poll question). Of course one can practice Aikido by themselves. Aikido is a way-of-life. Can you eat, think, and shit by yourself? Besides, take a look at the serene person performing slow, harmonious Tai Chi katas, or the one doing Yoga focusing on her breath while releasing thoughts of tension--THIS IS AIKIDO! Obviously we need the dojo and the use of an uke, but Aikido is daily living (and believe it or not folks, Aikido extends outside the dojo).