After decades of neglect, empiricism is returning to the philosophical scene. This book joins the trend, presenting an exposition and defense of an up to date version of empiricism. Earlier versions were brushed aside mainly by epistemic rationalists who believe in synthetic a priori truths and followers of W.V.O. Quine who think all truths are a posteriori. Aune rebuts the criticisms of both groups and defends an improved account of analytic truth. His last two chapters are concerned with empirical knowledge, the first with observation and memory and the second with the logic of experimental inference. In discussing observation and memory, Aune considers the skeptical problem raised by Putman's example of "brains in a vat." Although Putnam describes the captive brains as being fed erroneous sensory data by mad scientists with super computers, he argues that they cannot thereby entertain a skeptical problem about the world surrounding them. Aune argues that Putnam's argument is unsound and that the skeptical puzzle his example creates can be solved in a straightforward way by an inductive procedure accepted by present-day empiricists. Skepticism is not a problem for the empiricism he defends. This is the second edition of this book. Minor errors have been corrected and an additional issue is address in a new preface to the second edition.