We can't fill in answers to philosophical questions

The target article discusses the classic blind spot, scotomas, subjective c ontours. and other so-called filling-in phenomena. Its purpose is to evalua te the idea that some theories of filling-in amount to tacit acceptance of Cartesian materialism and a form of psychophysical isomorphism. Pessoa et a l. reject what is termed structural isomorphism as well as Cartesian materi alism, but claim that neural processes adduced as underlying filling-in may be acceptable without implying isomorphism. The article supports the idea of perceiving as an active constructive process. However, the various subth emes are not clearly related to each other. Topological psychophysical isom orphism is indeed untenable, but the tacit assumption that filling-in enjoy s any kind of unique status with respect to illuminating philosophical ques tions is doubtful.