The metaphysical extension of irrationalism may not be natural, but certainly implies a degree of difficulty in reaching for genuine metaphysical data.
One approach is simply to accept the 'blanknesses' of reality, a 'radical acceptance' as some have called it, as a way of knowing, perhaps with a Sartrean kind of terror, that 'what is there is there'.
Radical affirmation can even lead to irrational affirmations about the terrors lying (supposedly) behind the everyday facts.
But, of course, these 'facts' which we observe DO have some reality in our minds at least, because it is the thoughts we have which have significance for us.
There is a kind of sneaky corollary which is not so violent as the previous, which is that if we are able to rationalize all of our fears and suppositions about reality, then we would KNOW, we WOULD have some kind of truth-knowledge about real reality.
Perhaps this kind of truth would be over-contextual. But that is not to say that we cannot do our best to understand existence as it is portrayed for us.
To me, this is not a Sartrean gloom, but instead something viable that may bear fruit.
If knowledge is objective as I have argued---if exceptions bear out between the abstract and the real, relative to our position in reality, then we may use our knowledge, or conversely our sense of reality to determine our sense of reality or conversely our knowledge.
Thus, there are four potential categories to metaphysics:
1. Knowledge of Being (Obvious Knowledge) 2. Knowledge of Abstractions (Subtle Knowledge) 3. Sense of Being (Obvious Systems), and 4. Sense of Abstractions (Subtle Systems)