To know the other beings as psychical subjects is not to know them as human beings endowed with intellective-volitive activity. If we make distinction between animals and human beings, it does not necessarily carry a difference of degree, even in the level of their psychic life.

We understand from philosophy of man that our intellective-volitive activity inters into many relations strictly with experiential activity. The intentional object of knowing is taken in direct relation to the phantasm (that is to the perceived and the imagined). The question of existence, which leads to the evidential verification and to judgement, stands to the proposition of the concept in connection with experience. The judgement of the existence (an sit) itself carries the continuity from the experience, concept and affirmation. The practical judgement of value, which motivates the act of the will, refers itself purely to our experiential tendency. They are intentional objects of intellective-volitive activity. Here, we see the interrelationship of the different levels of activity, one presupposing the other.

As a result: through the experiential psychic activity, the intellective-volitive activity informs, organizes our behavior as gathered by perception from a confused or formless mode relative to the perceiving subject. Intelligence can therefore understand it, and then conceptualizing it, verifying it, and affirming it through judgement.

Now, there are two aspects of behavior, which, according to the majority of the authors, make the human specie specifically human: a) the use of means to reach an end and b) the expressivity, which renders communication possible within the species. By showing that the knowledge of means and ends as such and expression as means of communication are not explainable within the ambit of experience we can affirm that such a behavior imply intellective-volitive activities which are proper to the human being. However, these two aspects of behaviour are not only true to human beings. To a certain degree, it is also true to other earthly animals. But even if these two aspects are to certain measure present to animals, it does not necessarily imply the intellective-volitive activity.

1. Means-to-Ends.

There is a need to make a distinction between the behaviour structure means-to-end and the knowledge of means and ends as such. Here, we are inspired by the analysis made by Strasser - a phenomenologist disciple of Husserl - in his work Das Gemut (Phenomenology of Feeling.)

In both animal and human behavior, it is easily observable how some aspects lead from a non-causal way to the realization of successive and proportionate aspects. Put in classical terms, the behavior that manifest efficient causality in the proper sense. The analysis of tendential acts done by St. Thomas has been taken up by Strasser, which can be shown to have a unitary structure within the perceptual field. Love and hate toward the object proposed by the perceptual situation diversity respectively into repugnance and disgust, desire and delight according as the object is achieved or not. For as long as it is not yet achieved, hope and renunciation, audacity and timidity come into operation depending on the presence and degree of difficulty of obstacles toward the end.

There are other forms of behavior, however, which cannot be explained by a simple recourse to perception and tendential acts. The end desired does not enter into the present perceptual field nor the means to the tendential acts that follow the perception. Here we are dealing with the knowledge of end and its acceptance as such and the choice among possible means to reach it. When the means are not present in the actual situation, the agent creates them, and these means we call properly as instruments. The means-instruments and the ends properly thought of are outside the concrete context of perception. Thus, the creation of instruments and the reaching toward the end implies freedom of the human being from the concrete perceptual field and the immediate satisfaction of tendential acts and consequently manifests the intervention of intellective-volitive acts.

The human subject who confronts his situation in terms of means-to-ends also understands the behavior of another in a similar determined situation. He can take such behavior of the other on his own account and learn from it. And this is the normal way that the great part of the behavior of means-to-end is learned from others, since it is not invented independently.

2. Human Expression.

By expression we mean that aspect of behavior which leads the other to grasp its intention. Certain forms of behavior (songs of birds, bodily gestures, expression of pain) are immediate and punctual, needing no interpretation, and normally evoke spontaneous reactions on the part of others. We call these "signals". There are others, however, which may perceptively be identical with signals but are at the same time obviously expressive in intent as such. We refer to forms of behavior whose unique intent is to express an intention and to communicate through conventional means, especially the use of language.

The attitude involved here is similar to that of means-to-end, with the particularity that the end hereby realized is not in the outside world but within the subject himself/herself. These expressive behaviors we call signs and symbols according as the relationship between the signifier and the signified is arbitrary (sign) or one of similarity (symbol). In understanding the behavior that is expressive as such in terms of signs and symbols we can legitimise the spontaneous conviction that we know thereby the behavior of man since in it he exercise intellective-volitive activities.

In particular way, the use of language, of any language, whatsoever presupposes already the existence of a social group (linguistic community). But the active (speaking) and passive (hearing, understanding) use of language has to be learned although from the earliest age the child already emits and hears all the physical sounds which form part of the language he has to learn. Linguistic expression as such refers to known reality (i.e., it is informative and propositional) with the due presence or absence of emotive attitude toward the reality that the subject experiences. The meaning expressed in language are not so much objects as they exist in the world or the physical stimuli that arise from them but the contents or object of the psychical acts. The same reality can be given varied meanings. And these psychic contents are not only data of concrete experiences but are conceptual, with all their abstractness and universality, although their contents refer to concrete realities. This only shows the presence of intellective activity in the word and language.

3. Expression and Means-to-End with Animals.

All human beings belong biologically to unique specie. And all fabricate instruments. They possess a language and the capacity to understand the fabrication of language of other groups. Here we rather put ourselves the problem. If the two aspects of human activity allow us to base the reciprocal knowledge of each other as human beings, are they not also true to other animal specie? Because then individuals belonging to such specie would be recognized as subjects endowed of intellective-volitive activity.

The difficulty of a clear answer to the inquiry comes from the fact that every animal specie possesses a varied biological organism from that of other specie (there are millions of them), also the capacity and diverse needs, and thus an experiential psychical activity and a corresponding environment purely diverse. And moreover, it follows that their behavior is difficult to understand, even more difficult to measure that these species are larger than our own, that is considering their origin and evolutive status. Provisionally, basing ourselves on animal psychology and on ethnology (a biological discipline on animal behavior), we can affirm that means-to-an-end as such do not exist with animal behavior, that the expression does not seem to indicate eternal signals, and that certainly it does have anything as an abuse of language.

To look for superior forms of behavior, there is a need to go back to the types (the highest subdivisions of animal kingdom) of Metazoa ( multi-cellular organism) which are more complexed in its evolution. We have to go back to the type of anthropoid that includes the class of insects (longer and richer specie), and to the type of chordate, the sub-type and vertebrates which includes among other the class of uccelli and that of the mammals where the primordial order of the primates and especially the group of monkeys (anthropomorphic), the three specie of: Orang-utans, Chimpanzee, and the Gorilla.

Further, one must bear in mind the fundamental distinction between the innate behavior or instinctive (a pattern of stimuli that is a perceived configuration called releaser, related to a pattern or structure of behavior, wholly proper to all individuals of a given specie), and the learnt behavior. Also, if not always (cause by an observation or insufficient experimentation) we should know, if a given behavior is instinctive or learnt, and also if they exist at the beginning as instinctive then later refined and perfected through learning. This mentioned distinction is fundamental to the purpose, which here we fix in advance, because the instinctive behavior, by its very nature, does not require the intervention of the intellective-volitive activity in the subject that accomplishes it.

Animals, obviously, possess the capacity of resolving problems or overcome difficulty presented by their environment. This capacity is often called "intelligence" of animals. There are even marvellous behaviors of reaching an end such as the construction of a nest. But such behaviors are instinctive. They can be analyze in a chained of behavior, of the first, serving the second, and the following. When the chain is disturbed, they cannot correct it.

Among the closer behaviors, there is the need to discard those, where the apprehension seems to be "the conditioned type", revolving in wider apprehension, to that of the intuitive (insight learning), and to animal game.

The first, it consists in using, for the solution of the actual problem, the information acquired previously, and so without relation with reaching the result. The second, it stands in finding the solution for a mistake, without hesitations and tentatively disarranged. The animal game played by the mammals implies certainly a new liberation from the immediate biological needs. Although it is a game of exercise in the sense of Piaget, who distinguishes between the game of exercise, symbolic game, and game of rules, it seems to carry a certain dose of imagination (imitation exists certainly among the Chimpanzees). This take accounts the attitudes of the group in game.

But still what is proper to human beings cannot be equated to these behaviors. The experiential or psychical activities as demonstrated above are not sufficient to explain what is properly human. The impression of similarity with the human behavior is not enough. Now, the solutions to problem found by animals are always their respond to a perceived situation. Their orientation is spatial although at times complex.

The case suggested are those who use instruments. The marine otter (Enhydra lutris) takes from the base a big fistful stone. He swims on his back and holds the stone on his breast. Then he bangs the shell of the mollusc. At times, he holds the stone in consecutive dives. Certain birds bang the mollusc against the stones. Specie carries a pebble on the air and makes it fall on the egg of the Emu (a giant Australian bird) which has a shell too hard for its beak. There are many cases and examples that we can refer to. And here there is a need to recognize that certain behaviors which are flexibly and adaptably constructed. In the case of some insect and spiders, they explain themselves badly with only instinctive behaviour, but the thing remains to be studied further.

Besides the anthropomorphic monkeys, the use of instruments in the life of nature seems to be very rare. The unique cases observed refer themselves to chimpanzees: walnuts placed by their hand on the rock and crushed it by means of a rock.

But, in captivity, monkeys, in general and especially the Chimpanzees, use instruments, more by imitating the humans, e.g. the position of eating, etc. but also with apprehension more or less intuitive: cf. the experiment of Kohler, one of the founders of the Gestalt theory in 1917. The capacity of apprehension varies from one individual to another.

However, it does not always deal only with the perceived situations, the use of instruments reveals limits and imperfections that invalidate the suggestion that animals have taken the principle of the proportion between means and end.

Maurice Merleau-Ponty (existentialist and phenomenologist) explained such limits. He noted that the human perception is the indwelling of transcendence towards the world and things in themselves. It is "centrifugal", while that of the animal takes the environment only in the function of perceiving. It is "centripetal" (the equivalent distinction of Thomas between the relative experiential knowledge and intellectual knowledge in the full sense of the term, absolute, and the distinction between central knowledge and decentralised knowledge of Piaget). Because, the animal takes itself and its corporal schema as a nucleus of more functions. It cannot perceive other possibilities. The animal does not know how to use the principle of proportionality as it uses means to end. But human subjects are able to understand this principle. He uses it through the intervention of intellective-volitive.

To conclude, the animal behavior of means-to-end cannot be compared with that of the human being because the human being uses means-to-end as such.

Now, to the problem of expression-behavior between that of animals and human beings, the answer is easier, because the referred aspect of animal behavior is very much lacking in animals compared to the human beings. Expression is more proper to the human being, and this is evidenced by the use of language. Communication and dialogue is only proper to human beings, although in the case of animals we also consider the existence of signals. But such signals are only in the perceptual level or experiential level.

We, therefore, conclude this section with the affirmation that the means-to-end as such and expression as expression -–that which allows us to the other as human subject – it is a behavior exclusively proper of the human specie. That explains, as we will see, the absence in the animals of the third aspect which biology and psychology recognize as, at least in the macroscopic, typical of man and only of the human: the cultural diversity and progress and the behavioral change in time.