Designed to demonstrate Watson's theory of pure behaviourism - i.e. human behaviour is entirely formed through classical conditioning, and as infants humans are nothing more than blank disks.
Few subscribe to Watson's unbalanced view today, and subscribe to hybridized psychological theory, as different behaviours are a result of different processes. For example, no one has to teach a child what behaviour they should manifest when they are hungry, as it seems biologically they are pre-programmed to cry. Yet fears, or lack thereof, are generally subjective and often do depend on past experiences.
The later development of "Little Albert" is unknown, and Watson's experiment is considered grossly unethical by today's standards.