Flynn and certainty

Fetjenstein is undoubtedly one of the most influential philosophers of the twentieth century. The book "In Certainty," published in 1969, is considered the last work he wrote during his illness, in which he passed away. In this book, Fetjenstein addressed central issues in epistemology such as the nature of knowledge and skepticism. This book is an explanatory guide to it, and a necessary reading for students studying Fetjenstein, and for those studying epistemology and philosophy of language. The book "In Certainty" deals with common sense issues discovered by George Edward Moore, such as "the Earth is very old," "I have two hands," "the color of human blood is called 'red'," where the author in this explanatory guide will discuss Fetjenstein's rejection of considering these issues as empirical, as Moore did in his response to skepticism. For Fetjenstein, they are issues that seem empirical, fall outside the course of investigation, and are not subject to doubt. They are not a priori in the Kantian sense, and the analysis of their proximity or distance from the Kantian concept will be a broad and fascinating discussion by the author in this book. Fetjenstein believes that the boundary between a priori and empirical is vague and unclear.