St. Thomas Aquinas considers union with God the ultimate end because God is the highest good and the only source of perfect fulfillment and happiness (beatitude) for human beings—everything else is secondary and finite[4][8].
Philosophical Argument
- Aquinas argues that all human actions aim toward some good, but there must be a last end—a good sought for its own sake and not as a means to something else; otherwise, human life would lack any ultimate purpose[4][8].
- True perfection or happiness can only be found in something perfect, limitless, and completely fulfilling—which for Aquinas is God, since only God possesses infinite goodness and the power to fully satisfy human longing and intellect[4][5][8].
- Aquinas uses reason to show that created goods cannot be the final end: they are limited and cannot provide lasting fulfillment. Therefore, only knowledge and love of God—“the beatific vision”—is our final end and true happiness[4][5][8].
Theological Argument
- Aquinas teaches that the soul is designed to know and love its creator and that ultimate happiness is achieved in supernatural union with God (beatific vision): “Man’s last end, happiness, can consist in nothing else than the vision of the Divine”[7][8].
- He insists that union with God is not just the ultimate end for humans but for all creation. God is both the first cause and the final goal of every being[2][5].
- In this view, every lesser good is only a step toward that final and all-sufficient good—communion with God Himself[2][4][5].
Thus, for Aquinas, union with God is the ultimate end because God alone perfectly fulfills all human desires for truth, goodness, and happiness, and all things are ordered to God as their final purpose[4][8][5][7].
Sources [1] The True Ultimate End of Human Beings https://nlnrac.org/contemporary/new-natural-law-theory/primary-source-documents/the-true-ultimate-end.html [2] saint thomas and the ultimate purpose of creation https://theologicalstudies.net/wp-content/uploads/2022/08/2.1.4.pdf [3] 19 Aquinas: The Ultimate End - Oxford Academic https://academic.oup.com/book/5159/chapter/147792690 [4] Thomas Aquinas: Moral Philosophy https://iep.utm.edu/thomasaquinas-moral-philosophy/ [5] The Natural Desire of Human Beings for Beatitude https://credomag.com/article/the-natural-desire-of-human-beings-for-beatitude/ [6] The Key to Happiness Thomas Aquinas’s Summa … https://philolibrary.crc.nd.edu/article/key-to-happiness/ [7] thomas aquinas on man’s last end and the https://ijbms.net/assets/files/1737336406.pdf [8] Man’s last end (Prima Secundae Partis, Q. 1) https://www.newadvent.org/summa/2001.htm [9] a Sermon for the Feast of St. Thomas Aquinas, 28 January http://www.blackfriarscambridge.org.uk/2021/01/28/the-truth-which-has-called-us-a-sermon-for-the-feast-of-st-thomas-aquinas-28-january/ [10] Thomas Aquinas and John Duns Scotus on Individual Acts … https://philpapers.org/rec/OSBTAA