views. The opening of the book sets the stage for these inquiries by posing the question of whether any knowledge is so certain that it cannot be doubted. Russell highlights the complexities involved in our perceptions, using the example of a table to illustrate how what we see, feel, and hear about it may not correspond to any definitive reality. He emphasizes that our experiences are mediated through subjective sense-data, leading him to question the existence of physical objects independent of our perception. By the end of the opening chapter, he introduces the notion of 'sense-data'—the immediate experiences from our senses—and contrasts them with 'physical objects,' thus outlining the conceptual framework he will develop further in the subsequent chapters. (This is an automatically generated summary.)