From a pragmatic point of view, we can be said to have proved something if we can find a sound argument for it. Table 1 summarises these different kinds of deductive arguments, and table 2 provides an example of each. Fish are mammals. Fish are warm-blooded. Mammals are warm-blooded.
Mammals are cold-blooded.
Humans are cold-blooded. Fish are cold-blooded. Humans are not fish. Humans are warm-blooded. Humans are warm-blooded.