10. Fifthly, propositions are distinguished into _necessary_, that is, necessarily true; and true, but not necessarily, which they call _contingent_. A _necessary_ proposition is when nothing can at any time be conceived or feigned, whereof the subject is the name, but the predicate also is the name of the same thing; as _man is a living creature_ is a necessary proposition, because at what time soever we suppose the name _man_ agrees with any thing, at that time the name _living-creature_ also agrees with the same. But a _contingent_ proposition is that, which at one time may be true, at another time false; as _every crow is black_; which may perhaps be true now, but false hereafter. Again, in every _necessary_ proposition, the predicate is either equivalent to the subject, as in this, _man is a rational living creature_; or part of an equivalent name, as in this, _man is a living creature_, for the name _rational-living-creature_, or _man_, is compounded of these two, _rational_ and _living-creature_. But in a _contingent_ proposition this cannot be; for though this were true, _every man is a liar_, yet because the word _liar_ is no part of a compounded name equivalent to the name _man_, that proposition is not to be called _necessary_, but _contingent_, though it should happen to be true always. And therefore those propositions only are _necessary_, which are of sempiternal truth, that is, true at all times. From hence also it is manifest, that truth adheres not to things, but to speech only, for some truths are eternal; for it will be eternally true, _if man, then living-creature_; but that any _man_, or _living-creature_, should exist eternally, is not necessary. [Sidenote: Categorical & hypothetical.] 11. A sixth distinction of propositions is into _categorical_ and _hypothetical_. A _categorical_ proposition is that which is simply or absolutely pronounced, as _every man is a living-creature_, _no man is a tree_; and _hypothetical_ is that which is pronounced conditionally, as, _if any thing be a man, the same is also a living-creature_, _if anything be a man, the same is also not-a-stone_.