i8o The American Geologist. 
March, 1904. 
logical conception of the whole problem : while if the cube were 
made up for horizontal planes, that would suggest its geo- 
graphical aspect ; and the whole series of paleogeographies, 
horizontally stratified with respect to the vertical time line, 
would culminate in the geography of today. 
Objection is sometimes made to the plan of geography, as 
here set forth, that it involves hypotheses and theories, instead 
of being content with matters of fact, as the advocates of a 
more conservative method in geography suppose themselves 
to be. There is no doubt that geographical investigation of 
the kind here exposed does involve abundant theorizing, but 
that is one of its chief merits, for therein it adopts the methods 
of all inductive sciences. Furthermore, as between the progres- 
sive geographer, who candidly recognizes that he must theor- 
ize, and the conservative geographer, who thinks that he ob- 
serves facts only and lets theories alone, the chief difference is 
not that the first one theorizes and the second does not, but 
that the first one knows when he is theorizing and takes care 
to separate his facts and his inferences, to theorize logically, to 
evaluate his results, while the second one theorizes unconscious- 
ly and hence uncritically, and therefore fails to separate his in- 
ferences sharply from his facts, and gives little attention to 
the evaluation of his results. Geography has indeed suffered 
so long and so seriously from the failure of geographers to 
cultivate the habit of theorizing as critically as the habit of 
observing — studies of the atmosphere and the ocean still ex- 
•cepted, as above — that a strong recommendation must be given 
to the acquisition of the methods of theoretical investigation, 
in which deduction is an essential part, by ever}' one who 
proposes to call himself a scientific geographer. Let me give 
an example of the loss of time that has resulted from the fail- 
ure of geographers to develop the habit of theorizing. 
For forty years past there has been active discussion as to 
how far land forms in glaciated regions had been shaped by 
glacial erosion, but not till within five years has any geog- 
rapher clearly defined the deductive side of this problem. In 
order to determine wTiether land forms are carved by glacial 
erosion or not, two methods have been open : one is to observe 
the action of existing glaciers and thus determine whether 
they are competent or not to carve land forms : but this is dif- 
