If A is B, C is D; and if E is F, G is H.
Either C is not D or G is not H.
.'. Either A is not B or E is not F.
§ 783.
(1). Simple Constructive.
If she sinks or if she swims, there will be an end of her.
She must either sink or swim.
.'. There will be an end of her.
(2). Simple Destructive.
If I go to Town, I must pay for my ticket and pay my hotel bill.
Either I cannot pay for my ticket or I cannot pay my hotel bill.
.'. I cannot go to Town.
(3). Complex Constructive.
If I stay in this room, I shall be burnt to death, and if I jump
out of the window, I shall break my neck.
I must either stay in the room or jump out of the window.
.'. I must either be burnt to death or break my neck.
(4). Complex Destructive.
If he were clever, he would see his mistake; and
if he were candid, he would acknowledge it.
Either he does not see his mistake or he will not acknowledge it.
.'. Either he is not clever or he is not candid.