Some secondary commandments are deontological (concern actions rather than objectives and refer to our specific duties) but not absolutist. An example is given above. 36 However, as we shall see, Thomas Aquinas believes that there are cases in which it is morally acceptable to kill an innocent person, and therefore there may be occasions when it is morally acceptable to kill a fetus. But how can this be fair? Doesn`t this violate the supreme commandment for the preservation of life? The answer is to understand that for Thomas, an action is not only about what we do externally, but also about what we do internally (i.e. our motivations). With this distinction, he can show that, for example, killing an innocent person may be morally acceptable. 20 Thomas Aquinas also introduces what he calls human law, which leads to what he calls « secondary commandments. » This includes things like not driving more than 70 miles per hour on a highway, not kidnapping people, always wearing a helmet when riding a bike, not hacking someone`s bank account. Secondary commandments are not generated by our reason, but imposed by governments, groups, clubs, societies, etc.26 In short, because there are many moving parts of history. We now have the Eternal Law (God`s plans/purposes for all things), the Natural Laws (our participation in the Eternal Law leading to the primary commandments), the human laws (the people who make specific laws to grasp the truths of the laws of nature that lead to the secondary commandments) and now Thomas is finally introducing the Divine Law. Thomas said that slavery is not the natural state of man.
 He also argued that a slave was intrinsically equal to his master (Summa Theologiae Supplement, Q52, A2, ad 1). He distinguished between « natural slavery, » which benefits both master and slave, and « submissive slavery, » which deprives the slave of autonomy and, according to Thomas, is worse than death.  Thomas Aquinas` teachings on the right price, the right to tyrannicide and the equality of all sons of God baptized into the communion of saints imposed a limit on political power to prevent it from degenerating into tyranny. This system had a concern in the Protestant opposition to the Roman Catholic Church and in the « altruistic » responses to Thomism led by Kant and Spinoza. Moreover, in his treatise on law, Thomas distinguishes four types of laws: eternal, natural, human and divine. The eternal law is God`s decree that governs all creation: « The law, which is the highest reason, can only be understood as immutable and eternal. »  Natural law is human « participation » in eternal law and is discovered by reason.  Natural law is based on « first principles »: Some 200 years later, the Salamanca School expanded Thomas` understanding of natural law and just war. Since war is one of humanity`s worst evils, adherents of the school argued that it should only be used when it was necessary to prevent an even greater evil.
A diplomatic agreement is preferable, even for the most powerful party, before a war is started. Examples of « just war » include: From general principles, practical reason allows us to derive from secondary commandments. These are rules that govern our specific actions. It is the secondary commandments that make natural law appear deethical. They concern the rules of our actions, for example, « goods entrusted to others must be returned to their owner ». If I care about your money, I shouldn`t give it to charity, even if it would be good. That would be the wrong kind of action. It is my duty to give you back what has been entrusted to me. Thomas emphasized that « synderesis is the law of our mind because it is a habit that contains the rules of natural law, which are the first principles of human action. »   25 But if we look at what we have already said about natural laws and primary and secondary commandments, we might think that there is no need for God. If we can learn these primary commandments through rational reflection, then God simply falls out of history (remember the Euthyphro dilemma above). Thomas Aquinas calls animals stupid and that the natural order declared that animals were used by man. Thomas denied that humans have a duty of charity towards animals because they are not people.
Otherwise, it would be illegal to kill them for food. But people should always be charitable to them, because « cruel habits could affect our treatment of people. »   In February 1265, the newly elected Pope Clement IV summoned Thomas to Rome as papal theologian. In the same year, he was commissioned by the Dominican chapter of Agnani to teach at the Conventual Studium of the Roman monastery of Santa Sabina, founded a few years earlier, in 1222.  The Santa Sabina study then became an experiment for the Dominicans, the first provincial studium of the Order, a secondary school between the conventual studium and the studium generale. Before that time, the Roman province offered no special education, no art, no philosophy; only simple monastic schools with their basic theological courses for resident monks existed in Tuscany and Meridionale in the first decades of religious life. The new Santa Sabina Provincial Studium was to be a high school for the province.  Tolomeo da Lucca, Thomas` collaborator and first biographer, tells us that Thomas taught the full range of philosophical subjects, both moral and natural, to the Santa Sabina studies.  According to Thomas. » All acts of virtue are prescribed by natural law: for the reason of each one naturally commands him to act virtuously. But when we speak of virtuous acts considered in themselves, that is, in their own kind, not all virtuous acts are prescribed by natural law: for many things are done virtuously to which nature is not inclined at first; but which, by examination of reason, have been found by men to be conducive to a good life. Therefore, we must determine whether we are talking about virtuous actions from the point of view of virtue or as action in its kind.  40 Then why is the Son who kills the Father not in direct contradiction with the first commandment? Thomas Aquinas asks us to examine the difference between external action – the fact that the father was killed and inner action – motive. Reason is used to determine how we should live our lives.
We use our reason to fulfill the requirements of the primary commandments in order to achieve our purpose of doing good and avoiding evil. Secondary commandments are rules that are derived from primary commandments for practical reasons. In some cases, they refer to an action that is not natural and therefore always bad. Some actions were considered by Thomas Aquinas to be contrary to human nature. Reason would then give us absolute secondary rules that would always apply. For example, Thomas Aquinas believed that masturbation violated the natural purpose (telos) of sex, which is reproduction. This means that « do not masturbate » is an absolute secondary commandment. However, in the modern treatment of infertility, masturbation can be used to facilitate reproduction by artificial insemination by a husband. On this question, natural law theorists disagree on whether masturbation is not natural, and therefore they disagree on the secondary commandment « do not masturbate. » 31For Thomas Aquinas, everything has a function (a telos), and the good (the good things) are the actions that fulfill that function.
Some things like tassels and eyes do this naturally. However, man is free and therefore needs guidance to find the right path. This right path is found by argumentation and generates the « internal » law of nature.