# Why is the +3 oxidation state of Cerium more stable than +4?

For the 4f inner transition metals, +3 is the most common oxidation state (OS). Why is the +3 OS of cerium considered more stable than +4, at which it attains noble gas configuration?

Are you sure $\ce {Ce}$ (III) is really considered more stable than $\ce {Ce}$ (IV)? Since the most common cerium based compound is its dioxide so $\ce {Ce}$ (IV) is actually more stable.
In addition to that, $\ce{Ce}$ has 4 electrons in its outer orbital, thus leaving only one unpaired electron on the $\ce{6s}$ orbital doesn't sound really stable to me.
Well, as far my syllabus is concerned about, inspite of having F° configuration in $Ce(IV)$ it reduces itself easily to $Ce(III)$ as +3 O.S is predominantly stable in inner transitional metal series.