(1) It is necessarily true to say that “tomorrow has not yet come.”
(2) Socrates is necessarily a human being.
(3) If something is a human being, it is necessarily rational.
(4) Given the objective nature of my conviction about the matter, it is necessarily true that 13 is prime.
(5) Given the subjective nature of my conviction about the matter, it is necessarily true that I exist.
Type (1) consists in the fact that a statement as formulated cannot fail to be true. Type (2) consists in the fact that given a certain thing, its nature requires certain other things. Type (3) is hypothetical necessity — given one thing, another thing follows of necessity. Types (4) and (5) are claims that I am necessarily right about certain things, either in virtue of the objective nature of my conviction, or on account of its subjective nature, i.e. that which I apprehend concerning my conviction.
These types of necessity are not entirely distinct and it is not surprising that one can often formulate one kind of necessity in terms of another. In particular, types (4) and (5) are particular cases of (3).
It is questionable whether type (5) exists in reality, and if it does, its scope is extremely limited, perhaps to claims such as the one in the example. I will discuss this in the next post.