Romans 2:14 - Matthew Poole's English Annotations on the Holy Bible

Here he preoccupates the Gentiles plea. They might object, that having not the law, they could not transgress, nor be culpable in judgment: see Romans 4:15. To this he says, that though they had not the law written in tables of stone, as the Jews had, yet they had a law written in their hearts, which was a copy or counterpart of the other, and had in a manner the effects of it; for thereby they were instructed to do well, and debarred from doing evil, which are the two properties of all laws. Do by nature; nature is opposed to Scripture and special revelation: by the direction of the law, and light of nature, they did many things which the law of Moses commanded, and forbore many things which it forbade. Are a law unto themselves; i.e. they have in themselves such principles of reason and rules of equity, as are to them instead of a law, prescribing what they ought to do and avoid.