Objection 1. It would seem that all men have not the same last end. For before all else the unchangeable good seems to be the last end of man. But some turn away from the unchangeable good, by sinning. Therefore all men have not the same last end.
Objection 2. Further, man's entire life is ruled according to his last end. If, therefore, all men had the same last end, they would not have various pursuits in life. Which is evidently false.
Objection 3. Further, the end is the term of action. But actions are of individuals. Now although men agree in their specific nature, yet they differ in things pertaining to individuals. Therefore all men have not the same last end.
On the contrary, Augustine says (De Trin. xiii, 3) that all men agree in desiring the last end, which is happiness.
I answer that, We can speak of the last end in two ways: first, considering only the aspect of last end; secondly, considering the thing in which the aspect of last end is realized. So, then, as to the aspect of last end, all agree in desiring the last end: since all desire the fulfilment of their perfection, and it is precisely this fulfilment in which the last end consists, as stated above (Article 5). But as to the thing in which this aspect is realized, all men are not agreed as to their last end: since some desire riches as their consummate good; some, pleasure; others, something else. Thus to every taste the sweet is pleasant but to some, the sweetness of wine is most pleasant, to others, the sweetness of honey, or of something similar. Yet that sweet is absolutely the best of all pleasant things, in which he who has the best taste takes most pleasure. In like manner that good is most complete which the man with well disposed affections desires for his last end.
Reply to Objection 1. Those who sin turn from that in which their last end really consists: but they do not turn away from the intention of the last end, which intention they mistakenly seek in other things.
Reply to Objection 2. Various pursuits in life are found among men by reason of the various things in which men seek to find their last end.
Reply to Objection 3. Although actions are of individuals, yet their first principle of action is nature, which tends to one thing, as stated above (Article 5).
Source: Summa Theologica (New Advent)