Both Soren Kierkegaard and Ludwig Wittgenstein argued that there are some truths, located beyond the boundaries of rational understanding, which cannot be communicated directly to others. Wittgenstein was influenced by his reading of Kierkegaard's texts on these matters, and accordingly he, like Kierkegaard, has a place in his philosophy for the importance of inwardness in knowing paradoxical truths. A move of 'inwardness,' for Kierkegaard, is an action that requires a personal and absolute belief that can't be explained directly to others, while 'paradoxical truths', as Kierkegaard uses the phrase, refers to propositions that we regard as incomprehensible but true (one of his examples is the claim that Christ is both fully God and fully human). For Kierkegaard, we express inwardness when we actively and fully invest ourselves in believing a paradox. It is clear that Wittgenstein also believed that we can understand some things in a non-standard, non-objective way. The passages in which he discusses this kind of nonobjective understanding, however, are notoriously obscure.
Hoelle '05, Lisa, "Climbing Down the Ladder: Inwardness and Abstraction in Wittgenstein's Philosophy with Reference to Kierkegaard" (2005). Honors Projects. Paper 6.