It means that they gather and interpret their material fairly and argue about its interpretations rationally.
( It ( ( means ( that ( they ( ( ( ( ( ( gather and ) interpret ) ( their material ) ) fairly ) and ) ( ( argue ( about ( its interpretations ) ) ) rationally ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ means) (SBAR (IN that) (S (NP (PRP they)) (VP (VP (VB gather) (CC and) (VB interpret) (NP (PRP$ their) (NN material)) (ADVP (RB fairly))) (CC and) (VP (VB argue) (PP (IN about) (NP (PRP$ its) (NNS interpretations))) (ADVP (RB rationally))))))) (. .)))
The material is gathered hastily and is argued about irrationally.
( ( The material ) ( ( ( ( is ( gathered hastily ) ) and ) ( is ( argued ( about irrationally ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN material)) (VP (VP (VBZ is) (VP (VBN gathered) (ADVP (RB hastily)))) (CC and) (VP (VBZ is) (VP (VBN argued) (PP (IN about) (NP (NN irrationally)))))) (. .)))