### Step 1: English Answer
René Descartes, a pivotal figure in modern philosophy, is well known for his methodological skepticism, which includes doubting his senses. This skepticism is not an arbitrary act but a systematic approach to establishing a firm foundation for knowledge. Descartes' doubts are rooted in several considerations:


1. Illusions and Deceptions: Descartes points out that our senses can be deceived. For instance, a stick may appear bent when it is half-submerged in water, even though it is straight. Dreams can also be so vivid that they are indistinguishable from reality while we are experiencing them.


2. Fallibility of Human Perception: Descartes acknowledges that human perception is not infallible. People can be mistaken about the size, shape, or color of objects, especially under unusual conditions or due to certain medical conditions that affect perception.


3. The Demon Hypothesis: Descartes introduces a thought experiment involving an evil demon who is capable of deceiving him into believing things that are not true. This hypothetical scenario is used to question the reliability of all sensory experience.


4. The Search for Certainty: Descartes' primary goal in doubting his senses is not to reject them outright but to identify a foundation for knowledge that is immune to doubt. He seeks a form of knowledge that is so certain that it cannot be undermined by any conceivable scenario, including the possibility of deception by an evil demon.


5. The Role of Methodological Doubt: Descartes' doubt is not a psychological state but a methodological tool. It is a way of clearing away all preconceived notions to arrive at a clear and distinct understanding of what can be known with absolute certainty.


6. Meditations on First Philosophy: In his work "Meditations on First Philosophy," Descartes systematically doubts all his beliefs, including those based on the senses, to reach the bedrock of certainty. This process leads him to the famous statement "Cogito, ergo sum" (I think, therefore I am), which he takes as an indubitable truth because the very act of doubting requires a thinking being.

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The Mind-Body Distinction: Descartes' doubts also serve to highlight the distinction between the mind and the body. He argues that while the body may be subject to sensory deceptions, the mind, as the thinking thing, is not. This distinction is crucial for his dualistic philosophy, which posits that the mind and body are separate entities.

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Foundationalism in Epistemology: Descartes' approach is foundationalist, aiming to establish an unshakable foundation upon which all other knowledge can be built. By doubting everything that can be doubted, he aims to identify the foundational truths that are beyond doubt.

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The Role of Reason: While Descartes doubts the senses, he places great emphasis on the role of reason. He believes that through the use of reason, one can arrive at clear and distinct ideas that are not subject to the same level of doubt as sensory experiences.

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The Pursuit of Scientific Knowledge: Descartes' methodological doubt is also a response to the need for a more rigorous approach to scientific inquiry. He seeks to provide a secure basis for scientific knowledge that is not dependent on the fallible senses.

In summary, Descartes doubts his senses not because he believes they are always unreliable, but because he wants to establish a foundation for knowledge that is certain and beyond doubt. This foundational knowledge will then serve as the basis for a more secure understanding of the world through both reason and the senses.

### Step 2: Divider
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It is important to notice that Descartes only doubts his beliefs in order to find what is certain. Because certainty is the opposite of doubt, finding out what he can and can't doubt will establish what he can be certain of.read more >>