During first year I used to think about this question a lot. It seems defining things specifically and continually is the major pass time of the academic. At GCSE geography was half-remembered facts and a collection of well-chosen case studies, it was the separation of physical and human disciplines and had a focus on the physical world either through tectonics, the water cycle, and natural hazards or through international relations, economics, and a loose understanding of politics. At A level the case studies became more in-depth and the physical and human processes more complex but the jump from GCSE to A level geography was a simple layering of the same material. This version of geography is more familiar to many. Students who choose to do further reading may also have come across geopolitics, economic geography or other subjects which are the domain of some of the most well-known voices of human geography and conservation or geology may be physical geographies versions of these better-known fields. Certainly, when I was committing time to further reading in A level it was through Geopolitics and especially the work of Tim Marshal (His Prisoners of Geography is standard further reading). It was certainly a bit of a shock for my peers and me to be so introduced to the contentious divide between popular geography and academic geography with our professor warning us on Tim Marshal's leanings to environmental determinism, a big no-no in modern academic geography due to its associations with pseudo-science, social Darwinism and Eugenics. This introduced the question of what geography is if it isn’t academically defined in the same way as the popular geography so many A-level students read to get ahead.
Well, geography is a Greek word meaning Earth-writing from geo “earth” and “graphy” which is writing, the phrase we often use in geography then is geography is to “write the world”. A nice phrase but what does that mean? The world is complex and only gets more complex the more we learn, is it then geographies mission to write the world until completion? Most people agree that volcanoes are the subject of geography but what about the geography of cities such as urban geography, spatial analysis, and industrial geography. This was the question I liked to think about in lectures and when practising academic reading or writing, if geography is writing the world and geography is inherently about spatial relationships, at what level of magnitude does the spatial focus end? Does geography need to focus on the spatial relationship of atoms or is there a certain size limit to geographies study? Are emotional, cyber, and imaginary dimensions issues of geography or does this kind of interrogation of the subject only lead to geography as a uniform monopoly of the academic space? Some of these arguments are reconciled by the growing use of multi-disciplinary research across the hard sciences, social sciences, and humanities as well as the inter and intra collaboration of subjects.
Historically the definition of geography and its sub-disciplines such as cultural, feminist, Marxist, etc... have defined themselves differently for example Marxist geographers focus on a “means of production” and collective perspective to economic questions while Humanist geographers emphasise personal agency and individual action. These changing definitions and parameters to the extent of geographies reach are due to the discipline embracing the naturally subjective perception of human eyes and minds. One could argue this tension pushes geography towards a philosophical tendency in which infinite geographies can be created causing the subject to lose its identity or get lost in a never-ending changing and readjusting of definitions and academic borders. Ironically even this issue on academic subjects positioned in different places i.e., “hard science” and “humanities” has caught the attention of some abstract geographers who see the positionality of academic subjects as a deeply geographical idea.
This leaves a lot for an undergraduate student of geography who has just had the assurance of Prisoners of Geography stripped from them to think about and as geography journeys beyond the stars to study the planetary geomorphology of mars even the assurance of the limits of physical geography becomes an arbitrary ideal.
To me then geography is the entire extent of understanding reality through relative spatiality and positionality, it is a subject deeply woven into human perception whether that be through the physical “real” world or cyberspace, emotional space, or imagination the advent of virtual and augmented reality blurs these lines further and geography if it is going to “write the world” should pay close attention to what these changes mean for the subject.