Discuss the most important works by Stephen Toulmin.

The Uses of Argument (1958)
The Uses of Argument is arguably Toulmin's most influential book. In it, he argues that any approach to reasoning that attempts to arrive at certainties is impractical. Toulmin does not believe that theoretical arguments, which proceed through inferences and eventually arrive at a claim, guide understanding in helpful ways. He proposes a different approach that tests claims of interest to see if they can be justified.
The model he proposes begins with making a claim, then offering data or evidence to support it, and then providing any warranted information that is necessary to connect the evidence to the claim. These three pieces are necessary to any argument, according to Toulmin. Additionally, backing for sources, rebuttals to clarify the necessary conditions for the proposed claim, and any qualifiers of certainty may be added.
Human Understanding: The Collective Use and Evolution of Concepts (1972)
Human Understanding challenges the idea, put forward by Thomas Kuhn in The Structure of Scientific Revolutions, that ideological change happens in large, revolutionary leaps. While Kuhn thinks that different, contradictory paradigms exist and occasionally overtake each other, Toulmin argues that concepts evolve over time through a process of innovation and testing. In Toulmin's view, the most sound concepts will be repeated and survive.
This approach is meant to be neither relativist nor absolutist. Rather than denying context, as absolutists do, or arguing that varying contexts make concepts incomparable, Toulmin seeks an approach that allows the comparison of concepts from different contexts and attempts to understand which has a better ability to facilitate understanding.
Cosmopolis: The Hidden Agenda of Modernity (1990)
In Cosmopolis, Toulmin returns to his earlier argument against abstract and theoretical thinking. He expands his thoughts on the reasons he thinks these modes of thought are impractical, and proposes four "returns" that he believes would allow philosophy to address the practical issues of human life: the return to oral communication, to discussion of individual moral concerns, to a local historical and cultural context, and to questions which are immediately relevant.