necessary

Although I wished to think that all was false, it was yet necessary that I, who thus thought, must in some sense exist.

If it is absolutely necessary to use public computers, you should plan ahead and forward your e-mail to a temporary, disposable account.

But that a necessary being should give birth to a being with any amount, however limited, of moral freedom, is infinitely less conceivable than that parents of the insect or fish type should give birth to a perfect mammal.