Immanuel Wallerstein is a distinguished sociologist who has been a pioneer and leader in development of 'world-systems analysis'. In this book, he looks at knowledge somewhat more generally, emphasizing the uncertainties of knowledge and offering ideas for how to deal with such uncertainties. For the most part, I agree with his ideas.
His basic message is that our understanding of reality, scientific and otherwise, is unavoidably uncertain and approximate. This makes it hard to both assert and judge expertise in many domains, though we can still develop useful heuristics.
Part of the difficulty is that social systems are complex, blending both nomothetic (law-like) long-term trends and idiographic particularities. The result is that social systems must be understood historically (ie, narratively), with each historical social system having a bounded existence which generally ends when the system goes far from equilibrium and experiences a bifurcation which is chaotic, in the sense that the outcome can easily be influenced by many factors which would normally be considered relatively insignificant.
This complexity tends to make the future largely unpredictable, especially when the system is near a bifurcation point, as Wallerstein believes to be the case with our current 'capitalist world-economy'. This lack of predictability, combined with the fleeting nature of the present, may turn our focus towards the past (at least for historians), but even here uncertainty is rampant, with all historical work involving interpretation, pragmatically judged on the basis of plausibility and usefulness rather than some ideal of Platonic correctness.
The necessity of interpretation leads to the realization from cultural studies that our understanding, including science, is culture-bound and value-laden. As a result, scholarly work is inseparable from moral and political considerations, and our understanding must change with the times rather than counterproductively being locked into rigid theories. In this situation, we are wise to adopt a pluralistic approach, drawing on perspectives from outside the university system and from different cultures around the world.
Again, I tend to agree with Wallerstein's ideas, so I liked the book, and I think the review by Michael Mann sums it up nicely: "Wallerstein is always readable, often persuasive, and occasionally profound." My one complaint is that the book is a collection of papers rather than a proper monograph. This isn't disclosed until one reads the acknowledgments, and the result is quite a bit of repetition, along with a lack of genuine integration (somewhat ironic from an author who advocates breaking down boundaries for the sake of scholarly integration).
Nevertheless, Wallerstein is an important thinker and this is a worthwhile book, so I recommend it to anyone interested in a scholarly exploration of how we might develop a useful intellectual grasp of a world which is largely uncertain.