The reason for this was inexplicable (unless he wished to show that he, too, could have an opinion), but he urged that at this point the army should unite and there await the enemy.
Napoleon himself is no longer of any account; all his actions are evidently pitiful and mean, but again an inexplicable chance occurs.
When he afterwards recalled that impulse to unsolicited and inexplicable frankness which had very important results for him, it seemed to him—as it seems to everyone in such cases—that it was merely some silly whim that seized him: yet that burst of frankness, together with other trifling events, had immense consequences for him and for all his family.
There are no more uses of "inexplicable" in the book.
Show samples from other sources
With that he turned away and once again started inexplicably walking toward the wall.
James Dashner -- The Scorch Trials
For some inexplicable reason, those words popped into Thomas’s mind.