The present experiment was designed to examine so-called "thematic material effect" on logical performance in a reasoning task. In particular, the four cards problem was used to elicit preferences for various logical and illogical problem-solving strategies. The result showed that high performance in D'Andrade's "receipts task" was not due to thematic material effect but to cards shape not equivalent to that used in D'Andrade's "label factory task", and therefore the effect was more apparent than real in the sense that the high performance was caused by illogical problem-solving strategies. Based on such evidence, "schema theory" and "viewpoint theory" purporting to explain thematic material effect were then criticized. Finally, the author proposed a new theory called "degeneration theory" and cast doubt on the idea of domain-specific knowledge.