Mame Diarra Diagne
Philosophy of Law
2. Thoroughly explain Aquinas’ reasoning on whether the Natural law is
the same for all. Then explain his reasoning about in what ways the Natural law
cannot be rationally changed and in what ways the natural can be rationally
changed. Remember to give examples to illustrate his reasoning on this.
According to Aquinas in the fourth article of question 94 in, Summa Theologica, there is
speculative reason and practical reason. Speculative reason is the type of reason that occurs in
geometry, math, and some sciences. In this type of reasoning you have certainty. “Practical
reason, on the other hand, is busied with contingent matters, about which human actions are
concerned”. This type of reasoning deals with unchanging elements, but at the same time has a
lot of changing going on. (St. Thomas Aquinas, 40)
Aquinas says then, in terms of speculative matter, the truth is the same in all men, but not
known to all in regards to the conclusions. Aquinas explains this with the example of a triangle;
he says “thus it is true for all that the three angles of a triangle are together equal two right
angles, although it is not known to all”. In practical reason, Aquinas says that neither truth nor
morality is the same for all and equally known by all in regards to proper conclusions. Aquinas
says because of that it is right and true for all to act according to reason. (St. Thomas Aquinas,
41)
Finally, Aquinas says the Natural law is the same for all in a general way, as it relates to
the general principles of ethics. He says there is an ethic that is the same for all, known to
rational people. What is not the same for all? It is a moral law that you should return ones
personal property back to them. That is a general principle in Natural law, and it is always right
and unchangeable in ethics. Say you borrow a sharp tool from a neighbor, and before returning
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