When we use the word "man" not for the male gender or a male member of the human species, but for all members of the species, then we must a take a position that answers these questions:
1. Is man different in kind or only in degree from animals, especially other mammals?
2. If different in kind, not in degree, is that difference superficial and therefore reducible to a difference in degree, or is it radical and irreducible?
Two entities differ in degree if both have the same defining traits, but one has more and one has less of the same trait.
A superficial difference in kind between two things becomes a difference in degree by further analysis of the difference between them. Then the superficial difference in kind will be only an apparent, not a real difference in kind.
Consider, for example, the three states of matter: the solid as opposed to the liquid and the gaseous states, In its solid state, water can be walked on, but not in its liquid state. This would appear to be a difference in kind between the solid state of matter and the liquid state. But when we discover that these two states of matter are reducible to the velocity at which the molecules of water and of ice are in motion, we learn that the difference in kind between water and ice is only a difference in the degree of the velocity of molecular particles. It is only superficially a difference in kind and it is really reducible to a difference in degree.
The same applies to the superficial difference in kind between matter in its liquid state and matter in its gaseous states. It appears to be a difference in kind: we can take a cupful of water, but we cannot take a cupful of air.
When the difference in kind cannot thus be reduced to a difference in degree, it remains a difference in kind. The intellectual human mind has properties that cannot be reduced to a difference in degree from the minds of other mammals. The difference in kind is radical, not superficial, real, not apparent.
To claim that the difference between the human mind and the minds of other mammals is a radical difference in kind is to claim that the human mind has intellectual powers that the animal minds do not have at all. Other mammals minds can be explained in material terms, whereas the human mind's intellectual power cannot be. This is not to deny that we share other mental powers with animals, who, like ourselves, operate in the world of perceptual thought -- the world of things that are perceptually present, the world of sensation, imagination, and memory.
In addition, the human operates in the world of conceptual thought, where it deals with objects that are not perceptually present, nor can they ever be. This ability makes it a radical difference in kind.