Locke furthered a number of the central ideas expressed by others prior to him, specifically with regard to the issues of mind and matter.
He viewed the universe as one gigantic mechanical system and the distinctiveness of his theory lay in his effort to dethrone the dominant Aristotelian worldview that saw reality as a great machine subject to mechanical laws, specifically to what we know today as the laws of physics.
Locke explained thought as a series of ideas and he defined "idea" as something in the mind. Locke argued that the mind represents actually existing objects outside of the mind and through reasoning the mind confronts these ideas that are produced by external reality.
Locke defined "perception" as the relation of ideas and this resembles the work of Descartes; however, there are differences between the conclusions of the two. A primary difference between the conclusions of Locke and Descartes centered upon the different status Locke assigned to the senses.
Descartes argued that the senses deliver data and incline us to have certain beliefs but these beliefs do not actually count as knowledge. These beliefs according to Descartes must be interpreted and explained by reason before we can regard them as truth.
Reason therefore delivers the knowledge that operates on the senses according to Descartes.
For Locke, however, the senses actually deliver knowledge in their own right.
Descartes accepted the skeptic's challenge of the senses, but Locke dismissed these challenges and countered that the skeptic is casting doubt on the fundamental capacities of the human mind yet in so doing he is relying on the human faculties that he is condemning.
In short, Locke contended that the senses do not actually need reason in the sense that Descartes proposed, but actually supply us with reliable knowledge.
The senses in this manner can be trusted.
