Not knowing how to come up with a dissertation topic often brings students to writer’s block.
As it’s known, good topic is already half of the task done because you have to show your skills and walk an extra mile to make an additional research.
Always take enough time to look through ideas as you decide.
If you feel that theme is weak, start by looking into academic sources, evidence to support your facts or arguments.
Choose several to see if topic fits your aspirations and goals.