Complex sentence: Thus if the population of consumers increases, ceteris paribus the demand curve will shift out; if the proportion of consumers with a strong preference for a good increases, ceteris paribus the demand for that good will change.
Split into simpler sentences: Thus if the population of consumers increases ceteris paribus the demand curve will shift out. If the proportion of consumers with a strong preference for a good increases ceteris paribus the demand for the good will change.