Pseudoscience, common sense, and the problem of scale

Fundamentally, this is a problem of scale. What is common sense? It is a body of knowledge derived from common experience. Even toddlers know that objects always fall down not up and objects that are out of sight still exist. These rudimentary scientific observations form the bedrock of common sense. But for something to be common sense, it must take place on a level we can appreciate with our senses. Simply put, common sense can only tell us about events that are common to human experience.