After the ‘Socratic Method’ which poses one question after another until one arrives at a basic conclusion or truth, there is also a methodological tool in research and rational inquiry known as ‘Cartesian Doubt’ which serves as perhaps the second-most important methodological device or tool in the way of arriving at basic and “indubitable” conclusions and truths about the reality which we experience. The method is named after the early French Renaissance philosopher René Descartes, who developed the rationale for this particular method.
As someone wrote, Cartesian doubt translates into “proof beyond all possible doubt.” By raising “the broadest possible grounds for doubt” as someone argued, it follows that what we end up believing and knowing “will be that which cannot be doubted” and our beliefs and knowledge will then survive the skepticism and scrutiny of others. The basic aim, arguably, is to eliminate everything which can be doubted so that whatever is left is foolproof and true. And at the heart of the method is the questioning of our basic assumptions and beliefs in order to know if any of our assumptions and beliefs are true.
Cartesian doubt requires ‘constant questioning’ until we arrive at the basic or core assumptions and beliefs which we ourselves and others have taken to be ‘implicit’ all along. In a sense, Cartesian doubt is a method which gets us to the ideas that are necessary or foundational in order for anything to be known at all. The most basic and foundational idea of all, as Descartes argued, is the idea of our own existence (cogito ergo sum), given that our existence is proven by our mere ability and effort to question our existence. If we did not exist, then we would not have the ability to question our existence or to reason about anything. Certainty about one’s own existence then serves as a “starting-point” in order to “achieve indubitable knowledge of many other propositions as well.” And without this basic belief or idea about our own existence, nothing else could be known.
There are three stages to the method or process of Cartesian doubt. For one, there is a “withdrawal from the senses.” The foundation for empirical knowledge is the senses, and it is the senses upon which we rely in order to know about the external world. Withdrawal from the senses enables us to test whether the knowledge about the external world which we acquired through the senses is true or not. Descartes aimed at making the point that the knowledge and information we acquire about the external world solely through the senses is uncertain and unreliable, given that the senses can be deceptive as a result of changing perceptions. Hence, empirical knowledge is not an entirely reliable source for our understanding of the external world.
The second stage is known as the ‘dreaming hypothesis.’ This stage goes into the issue of our own capacity to understand or know what we know. Whereas the first stage consists of questioning the assumptions, beliefs, and opinions that we wield about the world, the second stage goes into the issue of our capacity to understand and know about the world. Descartes equated dreaming to reason as a means of doubting reality, given that dreaming uses the same mind as the senses in order to formulate our experiences and our understanding of reality. Abstract thoughts are ‘representations’ of the mind that are part of what exists in the external world, as Descartes argued. Hence, there are certain concepts or truths in the external world which are able to survive the test of scrutiny and doubt, given that our basic capacity to understand these concepts and truths are able to formulate such concepts or truths through abstract thinking.
And third, there is the “evil genius” or “imperfect creator” hypothesis. This hypothesis contends that there could be something in the external world which diverts us from having an accurate experience of reality. It is important to believe that there is a possibility of something being out there which diverts us away from an accurate experience of reality, because this belief will then prevent us from falling into the “bad habit” of believing everything that is out there without doubting and scrutinizing whatever it is that has been put forth to us by others. This much will perhaps suffice about the methodological device or tool known as ‘Cartesian doubt.’