We give again the proof of several classical results concerning the
cyclotomic approach to Fermat's last theorem using exclusively class field
theory (essentially the reflection theorems), without any calculations. The
fact that this is possible suggests a part of the logical inefficiency of the
historical investigations. We analyze the significance of the numerous
computations of the literature, to show how they are probably too local to get
any proof of the theorem. However we use the derivation method of Eichler as a
prerequisite for our purpose, a method which is also local but more effective.
Then we propose some modest ways of study in a more diophantine context using
radicals; this point of view would require further nonalgebraic investigations.Comment: Publications Math\'ematiques UFR Sciences Techniques Besan\c{c}on
2010 (2010) 85-11