A Positive Check refers to natural occurrences that increase the death rate in a population, thereby reducing the total number of people. This concept is crucial in understanding Malthusian Theory, as it suggests that when a population exceeds the capacity of resources, events such as famine, disease, or war will arise to decrease the population and restore balance. Positive Checks highlight the struggle between population growth and resource availability, emphasizing the potential for catastrophic consequences if unchecked population growth occurs.