A person who can't think for themselves is often referred to as "dependent," "indecisive," "suggestible," "gullible," or "easily influenced." They may rely heavily on others to make decisions or form opinions, lacking the ability to critically analyze information or situations independently. In some cases, such a person might also be described as having a "follower" mentality, meaning they tend to follow the opinions or actions of others without questioning or evaluating them.