Aristotle is known as a man endowed with a unique affinity for knowledge. And it is this affinity or rather this desire that leads him to endeavor into a multitude of fields of science or téxnai; he has a say in almost every type of science. Therefore he is the foundation or part of the foundation of many sciences, e.g., physics, philosophy, chemistry, biology, and perhaps it is this last science which has a particular effect on the development of his philosophical ideas. At least, this can be inferred apropos his theory in his Ethica Nicomachea.
As a biologist, Aristotle had to deal with florae and faunae. It must not have escaped his notice that living organisms are continuously striving towards a particular state, that they evolve in order to reach said state which one could call a state of ‘completion’ or ‘perfection’. Because of his investigations in the field of embryology, he observes how a fertilized egg after twenty days or so results in a chick, which in turn evolves into a chicken. Were one to ask Aristotle which came first, the chicken or the egg, surely he would respond that the egg is part of the process or means by which a chicken, the final product is reached. Moreover, since the chicken is the final product in this particular case of generation, the chicken must be more important.
Noticing this process also playing out in the generation of other plants and animals, i.e., a seed develops into a flower, he deduces his theory that man must similarly have an end as well. But it seems that Aristotle feels the need to reach the same conclusion, that man has an end, through the use of logic. He states that if man does not posses an end, then everything will be pursued ad infinitum, for there shall be no end; this eternal pursuit would be nothing more than a “vain and empty pursuit.” Therefore man, who is an animal, albeit a political animal, is also subject to the laws of nature and therefore must possess an end like all other organisms.
And if man has an end, as Aristotle seems to believe, what is this end to which all men strive and desire for? And can it be said that this end is what distinguishes one species from another? For in the generation of animals, during the first stages, e.g., the development of the embryo, it is rather difficult to distinguish one type of animal from another. As an organism progresses towards its end, distinguishing the animal is much facilitated. So, it can be said that man’s end is also the identifier of his species and that the attainment of this end is his assigned raison d’être for it is self-actualization. With regards to what or who decides what is to be end of each species, Aristotle remains ambiguous, at least in this particular work.
So man strives for his assigned end, an end or state that identifies him as man, separating him from the other beasts. But what is this end or this arxitektonikhê as Aristotle chooses to call it, since all other téxnai are subordinate to it? Without expressly stating it, Aristotle guides the reader into inferring that there is but a single end and that this end is felicity.
Aristotle reasons that the end of man is felicity because he says that man will seek other things, e.g., wealth, honor, in order to obtain felicity. Man does not seek felicity in order to obtain wealth or honor, but said things are sought for the sake of felicity, therefore this is the arxitektonikhê which man strives to obtain and what defines him as man.
Now a question arises, if a man is not happy or if he has not attained the chief good (felicity) to an appropriate and mean degree, is he a man? This is to say, since the purpose of man is to reach felicity, and it is felicity that which distinguishes him from the beasts, if he does not fully attain this characteristic, is he really a man? Aristotle does not investigate this aspect of man and his attainment of the master-art. But one can infer that because he distinguishes between different degrees of badness and goodness and just and unjust, than in one way or another, a man who does not reach self-actualization by reaching felicity is not a complete man. Therefore, would he possess another name since his ethos is different from the man who does attain felicity?
As was aforementioned, the end of a chick is to become a chicken, this end being the virtue of this particular animal. And in the process of the development of the chicken, different names are given to distinguish one stage from another: embryo; chick; chicken. We do not call it a chicken until it has obtained the characteristics of that which we properly call a chicken. Therefore, it would follow that man would by necessity require such categorization. A new nomenclature would be required to describe the different stages of man as he strives to reach his end point, to obtain the arxitektonikhê.
Finally, apropos what is good, why does man seek it? Aristotle describes man as possessing the rational soul – plants possess the nutritive soul and animals the nutritive and the sensible souls – and therefore man has the capacity to reason. Aristotle says that choices are made through the usage of deliberation and that we deliberate on those things that we can influence or bring about through our own will or actions. But deliberation uses reason – which is what separates man from plants and animals – and through the usage of reason, man is able to decide to seek the is good for the good is pleasant. And through reason, man is also able to deduce that he must seek the ultimate good, this arxitektonikhê, which is felicity. Thus because of his capacity to reason, man seeks the chief good above all other goods, since this is also his end and if he seeks other goods, it is only because he is aiming at felicity.