Induction works this way. You gather data from nature and then construct a theory. Someone using this method may be fooled into thinking they had collected all of the data that was available on that particular scientific phenomenon. However, because the Universe is infinite no amount of evidence can assure us that contrary evidence will not be found. Because of this fact, Karl Popper suggested that proper science must be accomplished by deduction.
Deduction involves the process of falsification of hypotheses.
In this process you develop a theory first and then try to find evidence that contradicts it. The scientific concepts of time and space are then explored and their relevance to Physical Geography is defined. Time and space are important to the study of Physical Geography because natural phenomena are influenced by these two universal factors. This topic then closes with the suggestion that Physical Geography is experiencing a radical change in investigative methodology. In the early years of Physical Geography, its practitioners were primarily interested in gathering descriptive facts about the world.