A hypothesis is presented and justified, according to which the essence of evil is considered as something that is unreasonably caused. The author's arguments are supported by the conceptual interrelation between the following three statements: 1) dialectically conflicting interpretation of evil; 2) traditional classification of evil as an unvalue; 3) suspicious attitude towards causality, which is characteristic of philosophical schools that are not strictly rationalistically oriented. By differentiating causation and founding, evil differs from good, which is understood in its essence as something unreasonably (extra casually) founded. Within the conceptual matrix of “causation and founding” some other meaningful ethical phenomena are determined, in particular, indifference. To support his hypothesis, the author uses, first of all, modernist style texts (or texts that are read as modernist ones) both of realistic and religious orientation, by interpreting them. In the meaningful explanation of the essence of evil as of something that is unreasonably caused, special emphasis is given to the F.M. Dostoevsky’s characters — Kirillov and Stavrogin. Attention is paid to the semantic nuances of the termed word combination (when bringing together the “unreasonableness” with the «involuntariness» and “inadvertence”). When drawing conclusions, the author emphasizes that evil cannot do in its manifestation without a causal action, which is absolutely formal, but at the same time solely reliably ascertained reason of an evil deed drowning in a lot of reasons that are empirically meaningful, but pretty speculative ones. Causality provokes and protects evil. Indifference being the thing that is reasonably not caused constitutes evil deeds that are turned inside out. Total indifference is indistinguishable from interminable evil. The “free” causality that is rationalistically confident cannot overcome nature's indifference to humans (which, however, can never be complete or thorough) and cannot support freedom (which is belittled by any causality) it the latter’s nurturing of good. And last but not least, good and evil are not that asymmetric so that a final victory of one over the other would be possible, and not that symmetric, too, so that the struggle for good against evil would become meaningless and hopeless.