True, if a person conducts an experiment on the freezing points of fresh water vs. salt water, that person will conclude that fresh water freezes at a higher temperature than salt water does. Once this fact is empirically established through experimentation, a person can ask questions about why fresh water freezes at a higher temperature than salt water and design another controlled experiment that studies various variables (i.e. amount of water, amount of salinity, composition of minerals in water etc.)