noun
sophistry; specious reasoning; false logic
Refers to arguments that sound plausible but are logically flawed or deceptive. Often used in critical or philosophical contexts. The word is relatively uncommon in everyday speech; 詭弁 (きべん) is a more frequent synonym.
彼の主張はえせ理屈に過ぎない。
His argument is nothing but sophistry.
その説明は一見もっともに聞こえるが、よく考えるとえせりくつだとわかる。
That explanation sounds plausible at first, but on reflection you realize it's specious reasoning.
詭弁 is the standard, more common word for 'sophistry' or 'sophism'. 似非理屈 is rarer and carries a slightly more colloquial or dismissive tone, emphasizing the 'fake' quality of the reasoning.
理屈 means 'reasoning' or 'logic' in a neutral sense. 似非理屈 adds the prefix 似非 (ese, 'pseudo-') to mark the reasoning as false or deceptive.
Compound of 似非 (ese, 'pseudo-', 'false') and 理屈 (rikutsu, 'reasoning', 'logic'). 似非 is an ateji spelling for the native Japanese prefix ese, which indicates something fake or inferior. The exact historical derivation of ese is uncertain, but it has been used since the Heian period.