Pilpul

Pilpul (, loosely meaning 'sharp analysis'; ) is a method of studying the Talmud through intense textual analysis in attempts to either explain conceptual differences between various halakhic rulings or to reconcile any apparent contradictions presented from various readings of different texts. The word "pilpul" has entered English as a colloquialism used by some to indicate extreme disputation or casuistic hairsplitting.
Sources.
The requirement for close derivation of the conceptual structures underlying various Jewish laws, as a regular part of one's Torah study, is described by Maimonides as follows:
Other such sources include "Pirkei Avot", the Babylonian Talmud, 
Rashi,
and the Alter Rebbe.
Narrow definition.
In the narrower sense, "pilpul" refers to a method of conceptual extrapolation from texts in efforts to reconcile various texts or to explain fundamental differences of approach between various earlier authorities, which became popular in the late fifteenth and early sixteenth centuries: its founders are generally considered to be Jacob Pollak and Shalom Shachna. "Pilpul" was defined by Heinrich Graetz as "the astonishing facility of ingenious disquisition on the basis of the Talmud."
Opposition.
Many leading rabbinic authorities have harshly criticized this method as being unreliable and a waste of time, and it is regarded by some as having been discredited by the time of the Vilna Gaon. A common criticism is that those who used this method were often motivated by the prospect of impressing others with the sophistication of their analysis, rather than by a disinterested pursuit of truth; such students, it was held, did not apply appropriate standards of proof in obtaining their conclusions (if any), and frequently presupposed conclusions that necessitated unlikely readings (interpretations) of "proof-texts". As such, "pilpul" has been derogatorily called "bilbul", Hebrew for "confusion".
The Maharal of Prague, in a famous polemic against "pilpul", wrote: "It would be better to learn carpentry or another trade, or to sharpen the mind by playing chess. At least they would not engage in falsehood, which then spills over from theory and into practice..."
Current methods.
In the late eighteenth and nineteenth centuries, "pilpul" in this narrow sense was largely superseded by the analytic methods pioneered by the Lithuanian school, in particular the Brisker derech. However, many people consider these methods too to be a form of "pilpul", though the practitioners of the analytic method generally reject the term. Before World War II, both the old and the new kinds of "pilpul" were popular among Lithuanian and Polish Jews. Since then, they have become prominent in most Ashkenazi and many Chassidic yeshivas.
See .