Thomas Aquinas

===Ethics===
{{see also|Christian ethics}}
{{Redirect|Eternal law|2012 fantasy drama series|Eternal Law}}
Thomas was aware that the Albigensians and the Waldensians challenged moral precepts concerning marriage and ownership of private property and that challenges could ultimately be resolved only by logical arguments based on self-evident norms. He accordingly argued, in the Summa Theologiae, that just as the [[first principle]] of demonstration is the self-evident principle of noncontradiction ("the same thing cannot be affirmed and denied at the same time"), the first principle of action is the self-evident ''Bonum'' precept ("good is to be done and pursued and evil avoided").<ref>{{Cite book |last=Aquinas |first=Thomas |title=Summa Theologica, I-II q. 94, a. 2c |publisher= |url=https://www.newadvent.org/summa/2094.htm}}</ref>

This natural law precept prescribes doing and pursuing what reason knows is good while avoiding evil. Reason knows what is objectively good because good is naturally beneficial and evil is the contrary. To explain goods that are naturally self-evident, Thomas divides them into three categories: substantial goods of self-preservation desired by all; the goods common to both animals and humans, such as procreation and education of offspring; and goods characteristic of rational and intellectual beings, such as living in community and pursuing the truth about God.<ref>{{Cite book |last=Aquinas |first=Thomas |title=Summa Theologica I-II q. 94, a. 2.}}</ref>

To will such natural goods to oneself and to others is to love. Accordingly, Thomas states that the love precept obligating loving God and neighbour are "the first general principles of the natural law, and are self-evident to human reason, either through nature or through faith. Wherefore all the precepts of the decalogue are referred to these, as conclusions to general principles."<ref>{{Cite book |last=Aquinas |first=Thomas |title=Summa Theologica I-II q. 100, a. 3 ad 1.}}</ref><ref>{{Cite journal |last=Lemmons |first=R. Mary Hayden |date=1992 |title="Are the Love Precepts Really Natural Law's Primary Precepts?" |url=https://www.pdcnet.org/acpaproc/Proceedings-of-the-American-Catholic-Philosophical-Association |journal=Proceedings of the American Catholic Philosophical Association |volume=LXVI |pages=45–71 |doi=10.5840/acpaproc1992661 |via=Philosophy Documentation Center}}</ref>

To so focus on lovingly willing good is to focus natural law on acting virtuously. In his ''Summa Theologiae'', Thomas wrote:

{{blockquote|Virtue denotes a certain perfection of a power. Now a thing's perfection is considered chiefly in regard to its end. But the end of power is act. Wherefore power is said to be perfect, according as it is determinate to its act.<ref>{{Cite book |chapter-url= http://ccel.org/ccel/aquinas/summa.FS_Q55_A1.html#FS_Q55_A1-p8 | author= Thomas Aquinas| title= Summa Theologica | chapter= Question 55, Reply 1 |via= ccel.org |access-date=2012-02-02}}</ref>}}

Thomas emphasized that "[[Synderesis]] is said to be the law of our mind, because it is a habit containing the precepts of the natural law, which are the first principles of human actions."<ref name=SEP4 /><ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica| volume= First Part of the Second Part| chapter= Question 94, Reply Obj. 2}}</ref>

According to Thomas "...{{nbsp}}all acts of virtue are prescribed by the natural law: since each one's reason naturally dictates to him to act virtuously. But if we speak of virtuous acts, considered in themselves, i.e., in their proper species, thus not all virtuous acts are prescribed by the natural law: for many things are done virtuously, to which nature does not incline at first; but that, through the inquiry of reason, have been found by men to be conducive to well living." Therefore, we must determine if we are speaking of virtuous acts as under the aspect of virtuous or as an act in its species.<ref name="Thomas Aquinas">{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Article 3}}</ref>

Thomas defined the four [[cardinal virtues]] as [[prudence]], [[temperance (virtue)|temperance]], [[justice]], and [[courage|fortitude]]. The cardinal virtues are natural and revealed in nature, and they are binding on everyone. There are, however, three [[theological virtues]]: [[faith]], [[hope]], and [[charity (virtue)|charity]]. Thomas also describes the virtues as imperfect (incomplete) and perfect (complete) virtues. A perfect virtue is any virtue with charity, charity completes a cardinal virtue. A non-Christian can display courage, but it would be courage with temperance. A Christian would display courage with charity. These are somewhat supernatural and are distinct from other virtues in their object, namely, God:

{{blockquote|Now the object of the theological virtues is God Himself, Who is the last end of all, as surpassing the knowledge of our reason. On the other hand, the object of the intellectual and moral virtues is something comprehensible to human reason. Therefore the theological virtues are specifically distinct from the moral and intellectual virtues.<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 62, Article 2| chapter-url=http://ccel.org/ccel/aquinas/summa.FS_Q62_A2.html#FS_Q62_A2-p6 | via= ccel.org |access-date=2012-02-02}}</ref>}}

Thomas Aquinas wrote "[Greed] is a sin against God, just as all mortal sins, in as much as man condemns things eternal for the sake of temporal things."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | volume= Second Part of the Second Part| chapter= Question 118, Article 1 |chapter-url= http://www.ccel.org/a/aquinas/summa/SS/SS118.html#SSQ118A1THEP1 |via= ccel.org| access-date= 26 October 2018}}</ref>

Furthermore, in his ''[[Treatise on Law]]'', Thomas distinguished four kinds of law: eternal, [[Natural law|natural]], human, and [[Divine law|divine]]. ''Eternal law'' is the decree of God that governs all creation: "That Law which is the Supreme Reason cannot be understood to be otherwise than unchangeable and eternal."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 91, Article 1}}</ref> ''Natural law'' is the human "participation" in the ''eternal law'' and is discovered by [[reason]].<ref>{{Cite book |url=https://archive.org/details/ethics00loui |title=Ethics: Discovering Right and Wrong |last=Pojman |first=Louis |publisher=Wadsworth Publishing Company |year=1995 |isbn=0-534-56138-1 |location=Belmont, California |author-link=Louis Pojman}}</ref> ''Natural law'' is based on "[[first principles]]":

{{blockquote|. . . this is the first precept of the law, that good is to be done and promoted, and evil is to be avoided. All other precepts of the natural law are based on this . . .<ref>{{Cite book |chapter-url= http://ccel.org/ccel/aquinas/summa.FS_Q94_A2.html#FS_Q94_A2-p7 | author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Article 2 |via= ccel.org |access-date=2012-02-02}}</ref>}}

Whether the natural law contains several precepts, or one only is explained by Thomas, "All the inclinations of any parts whatsoever of human nature, e.g., of the concupiscible and irascible parts, in so far as they are ruled by reason, belong to the natural law, and are reduced to one first precept, as stated above: so that the precepts of the natural law are many in themselves, but are based on one common foundation."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Second Article, Reply Obj. 2}}</ref>

[[File:Tommaso Aquino - Francisco de Zurbarán.jpg|thumb|upright=.7|Detail of ''[[The Apotheosis of Saint Thomas Aquinas]]'' by [[Francisco de Zurbarán]], 1631]]
The desires to live and to procreate are counted by Thomas among those basic (natural) human values on which all human values are based. According to Thomas, all human tendencies are geared towards real human goods. In this case, the human nature in question is marriage, the total gift of oneself to another that ensures a family for children and a future for mankind.<ref>{{Cite book |chapter-url= http://www.corpusthomisticum.org/snp4027.html |volume= IV, Commentary| title=In Sententiae |chapter= d. 27 q. 1 a.1 |last=Aquinas |first=Thomas |via= corpusthomisticum.org |access-date=21 September 2011}}</ref> He defined the dual inclination of the action of love: "towards the good which a man wishes to someone (to himself or to another) and towards that to which he wishes some good".<ref name="newadvent.org">{{Cite book |chapter-url=http://www.newadvent.org/summa/2026.htm#article4 | author= Thomas Aquinas| title= Summa Theologica | chapter= STh I–II, 26, 4, corp. art |via= New Advent |access-date=30 October 2010}}</ref>

Concerning Human Law, Thomas concludes, "...{{nbsp}}that just as, in the speculative reason, from naturally known indemonstrable principles, we draw the conclusions of the various sciences, the knowledge of which is not imparted to us by nature, but acquired by the efforts of reason, so to it is from the precepts of the natural law, as from general and indemonstrable principles, that human reason needs to proceed to the more particular determination of certain matters. These particular determinations, devised by human reason, are called human laws, provided the other essential conditions of law be observed{{nbsp}}..." Human law is [[positive law]]: the natural law applied by governments to societies.<ref name="Thomas Aquinas"/>

Natural and human law is not adequate alone. The need for human behaviour to be directed made it necessary to have Divine law. Divine law is the specially revealed law in the [[scriptures]]. Thomas quotes, "The Apostle says (Hebrews 7.12): The priesthood being translated, it is necessary that a translation also be made of the law. But the priesthood is twofold, as stated in the same passage, viz, the levitical priesthood, and the priesthood of Christ. Therefore, the Divine law is twofold, namely, the Old Law and the New Law."<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter= Question 94, Article 5}}</ref>

Thomas also greatly influenced Catholic understandings of [[mortal sin|mortal]] and [[venial sin]]s.

Thomas Aquinas refers to animals as dumb and that the natural order has declared animals for man's use. Thomas denied that human beings have any duty of charity to animals because they are not persons. Otherwise, it would be unlawful to kill them for food. But humans should still be charitable to them, for "cruel habits might carry over into our treatment of human beings."<ref>{{Cite book |title=The Oxford Companion to Philosophy |year=1995 |editor-last=Honderich |editor-first=Ted |location=Oxford |pages=35–36 |chapter=Animals: Peter Singer |chapter-url=http://www.utilitarian.net/singer/by/1995----04.htm | via= utilitarian.net }}</ref><ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | volume= Second Part of the Second Part| chapter= Question 64. Article 1}}</ref>

Thomas contributed to [[History of economic thought#Economic thought in the Middle Ages (500–1500 AD)|economic thought]] as an aspect of ethics and justice. He dealt with the concept of a [[just price]], normally its market price or a regulated price sufficient to cover seller [[costs of production]]. He argued it was immoral for sellers to raise their prices simply because buyers were in pressing need of a product.<ref>{{cite book| author= Thomas Aquinas| title= Summa Theologica | chapter-url= http://www.saylor.org/site/wp-content/uploads/2012/06/ECON301-2.1.2-1st.pdf |chapter= Of Cheating, Which Is Committed in Buying and Selling| translator= The Fathers of the English Dominican Province| access-date= 19 June 2012}}</ref><ref>{{Cite book |title=The New Palgrave: A Dictionary of Economics |title-link=The New Palgrave: A Dictionary of Economics |last=Gordon |first=Barry |year=2009 |volume=1 |chapter=Aquinas, St Thomas (1225–1274) |orig-year=1987 |page=100}}</ref>