Problem of induction is a problem in philosophy that comes up when people try to figure out how we know that something is true. People use induction when they make guesses about what will happen in the future based on what has happened in the past. For example, if the sun has come up every day in the past, we might assume it will come up tomorrow. But this assumption could be wrong - the sun could not come up tomorrow, or ever again. The problem of induction is to figure out how we can trust that something that has happened in the past will happen in the future.