In law school, I presented a paper on jurisprudence, fundamental rights and the Supreme Court of the United States to my seminar on law, history and philosophy. As part of my research into such intellectually-stimulating realms of natural law and legal positivism, I would often come across writers who had examined the natural law espoused by John Locke in his Two Treatises of Government and compared it to his arguments in An Essay Concerning Human Understanding against innate ideas. Most of these writers were puzzled by the apparent contradiction between the two concepts.
As opposed to the rationalists who thought that humankind was born with certain innate ideas, Locke thought that humans were born with no ideas at all and that only through sensory experience could they gain ideas and structure them into increasing mixed and complex ideas. Many have probably heard this referred to as the tabla rasa. Natural law is a theory of jurisprudence that holds that law is a body of rules found in nature that are independent from the customs and mores of mankind. To the extent that man-made laws conflict with this natural set of laws, the man-made laws were unjust. In recent memory, the most famous declaration of natural law was when Dr. Martin Luther King, Jr. famously quoted Augustine in his “Letter from a Birmingham Jail” and stated that one had a moral responsibility to disobey an unjust law, albeit nonviolently.
Returning to the apparent Lockean contradiction of tabla rasa and natural law, it appears that Locke is saying on the one hand, that all ideas and knowledge come from experience, and are not innately existent in humans, but on the other hand, to be arguing that there is a system of laws that are self-evident to all humankind. It quickly became apparent to me that there was no contradiction and that those who thought otherwise had not bothered to read what Locke had actually wrote. (Although to be fair, I must admit that Locke’s Essay is a difficult read. It’s not because it is abstruse, but because it is so dense and wordy.)
Further adding to the apparent contradiction was that Locke was dismissive of the earlier philosophical work of the Scholastics, chief of whom was St. Thomas Aquinas who championed natural law. Locke was especially dismissive of their work as it related to their attempts to posit real essences in objects. Locke felt that objects only had real essences in our ideas, not within the object itself. Locke argued that universal terms such as ‘man’ or ‘dog’ only applied to groups of objects and not to any one specific man or any one specific dog. The human mind ordered objects and combined simple ideas into complex ones. But this did not mean that he thought that natural law was somehow a real essence of the world.
To properly frame Locke’s arguments, however, you have to look at the intellectual climate of his time. Instead of calling branches of knowledge by their modern names, philosophers of the time referred to natural philosophy, which later became science, and natural religion, which later become teleological theology. It is no surprise, therefore, that a theory of jurisprudence would be labeled ‘natural’ law. Philosophers looked to the general success of natural philosophy in uncovering laws about the physical nature of the universe and optimistically extended those methods and conclusions to other scholarly endeavors.
In this light, it is easy to see that Locke thought that people were not born with an innate notion of gravity or planetary movement, that through experience (and application of reason, viz., the scientific method) they would come to understand the law of gravity or the law of planetary movement. These laws of physics existed outside of the human mind, yet they were discoverable by it. Applying this rationale to the law and human rights, Locke felt that through experience and the use of reason, people could arrive at an undisputed notion of what the natural law was. If there was any disagreement over what the law should be, it was because of flaws within human’s minds and the general complexity involving 'complex ideas' (as he defined it), not because law was a man-made creation.
Moral of this post: Before you discourse on a writer’s ideas, make sure that you have actually read what the writer had written before commenting on those ideas. Otherwise you come across as a lazy scholar.