Editing Subject and object (philosophy) (section)

=== Cartesian dualism ===
The formal separation between subject and object in the Western world corresponds to the [[Cartesian dualism|dualistic framework]], in the [[early modern philosophy]] of [[René Descartes]], between [[Mental substance|thought]] and [[Res extensa|extension]] (in common language, [[Mind–body problem|mind and matter]]). Descartes believed that thought ([[objectivity and subjectivity|subjectivity]]) was the essence of the [[mind]], and that extension (the occupation of space) was the essence of matter.<ref>{{cite book|last=Descartes|first=René |title=The Principles of Philosophy|url=http://www.gutenberg.org/cache/epub/4391/pg4391-images.html|section=LIII|access-date=19 July 2016}}</ref> For modern philosophers like Descartes, [[consciousness]] is a state of [[cognition]] experienced by the subject—whose existence can never be doubted as its ability to doubt (and think) [[Cogito ergo sum|proves]] that it exists. On the other hand, he argues that the object(s) which a subject perceives may not have [[reality|real]] or full existence or value, independent of that observing subject.