How do we justify logic? If logic is a method to knowledge, then logic is subject to what knowledge is subject to, namely an interrogation.
What is logic? A system by which facts are ascertained? What are these facts? But... What is it that logic represents or illustrates? That which eludes a superlative representation? Yes, logic is therefore abstraction.
But this abstraction has its placeholders and aspects of existence can be substituted so to assume a logical intelligibility, but never does logic have anything to do with truth, absolute truth, only a truth that is imaginary.
Knowledge is only as if it were knowledge.