A movement paradox is a phenomenon of grammar that challenges the transformational approach to syntax.
A transformational approach to syntax will explain all sorts of discontinuities (e.g. wh-fronting, topicalization, extraposition, scrambling, inversion, shifting) in this manner in terms of movement.
They occur when the "moved" constituent is acceptable in its derived position but not in its base position, e.g.[2] These data are difficult to explain in an analysis based on movement, since it is not evident how the b-sentence can be grammatical each time if it is derived by a movement operation applied to the corresponding a-example.
To state the problem in other words, the movement analysis of the b-sentences has to explain the unexpected fact that the a-sentences are bad.
The so-called long passive in German presents a movement paradox that revolves around competing case forms, e.g.[3] On the assumption that the noun phrase den Wagen is in its base position in the a-sentence, this noun phrase must be in a derived position in the other two sentences.