Is there any such thing as human law?

It seems that there is no such thing as human law:

Objection 1:  As has been explained (a. 2), natural law is a participation in eternal law.  But as Augustine says in De Libero Arbitrio 1, all things are completely ordered through eternal law.  Therefore, natural law is sufficient for ordering all human affairs.  Therefore, it is unnecessary for there to be any such thing as human law.

Objection 2:  As has been explained, (q. 90, a. 1), law has the character of a measure.  But human reason is not the measure of things; just the opposite, as Metaphysics 10 insists.  Therefore, there cannot be a law that proceeds from human reason.

Objection 3:  As Metaphysics 10 says, a measure should be absolutely fixed (certissima).  But human reason’s dictates about things to be done are not fixed, since according to Wisdom 9:14, “The thoughts of mortal men are fearful and our counsels uncertain.”  Therefore, there cannot be a law that proceeds from human reason.

But contrary to this:  In De Libero Arbitrio 1 Augustine posits two kinds of law, one eternal and the other temporal, and he calls the latter ‘human law’.

I respond:  As was explained above (q. 90, a. 4), law is dictate of practical reason.  Now practical reason and speculative reason proceed in similar ways, since, as was established above (q. 90, a. 1), both proceed from given principles to given conclusions.  Accordingly, then, just as, in the case of speculative reason, conclusions in the diverse sciences, which are not naturally known to us but are instead discovered by the activity of reason, are brought forth from naturally known indemonstrable principles, so too from the precepts of natural law, which are, as it were, common and indemonstrable principles, human reason must proceed to determine certain matters in a more particular way.  And these particular determinations, devised by human reason, are called human laws—assuming the preservation of all the other conditions, described above (q. 90, a. 4), that are relevant to the nature of law.
Thus, in his Rhetorica Tully says, “The beginnings of justice came from nature; next, certain things came to be customs because of their advantageous nature; afterwards, fear and reverence sanctioned both what had come from nature and what had been approved by custom.”

Reply to objection 1:  Human reason is incapable of participating fully in the ordering (participare plenum dictamen) of divine reason; rather, it participates in its own way and incompletely.  And so just as, in the case of speculative reason, there is in us, through our natural participation in God’s wisdom, a cognition of certain common principles but not a proper cognition of every truth such as is contained in God’s wisdom, so too, in the case of practical reason, man naturally participates in eternal law with respect to certain general principles, but not with respect to the particular determination of singular acts, even though the latter are contained within the eternal law.  This is why it is necessary for human reason to proceed further to the particular sanctions contained in laws.

Reply to objection 2:  Human reason is not on its own (secundum se) a rule with respect to things; instead, the principles that are naturally instilled in human reason are general rules and measures of all the things which are to be done by man and with respect to which natural reason is the rule and measure—even though it is not a measure of those things that stem from nature.

Reply to objection 3:  Practical reason is concerned with actions (operabilia), which are singular and contingent, and not with necessary things like those which speculative reason is concerned with.  And so human laws cannot have the sort of infallibility that the demonstrated conclusions of the sciences do.  Nor is it necessary that every measure should be in every way infallible and fixed; rather, it should be as fixed as its possible within its own genus.