Critics like C.E. Vaughan, George H, Sabine and Peter Laslett have argued that the notion of natural law cannot be reconciled with the overall empiricism of Locke which shows itself in his criticism of innate ideas and his theory of origin of knowledge in sense-experience and election. But a careful analysis of Locke’s epistemology leads to the conclusion that the blanket label ’empiricist’ is not properly applicable to Locke and his theory contains important rationalist elements.
He expressly says that his criticism of innate ideas should not be understood to imply the rejection of natural law. Moreover, only sense experience cannot provide us with certain knowledge, that is knowledge,’ in the true sense, without the creative participation of mind.
His theory of knowledge, at least in its broad perspective and aim, closely resembles, the critical philosophy of Kant, and it has to be clearly distinguished from the atomistic sensationalism of the British empiricists who followed him.
Another element of Locke’s theory which is supposed compare the coherence and integrity of his notion of Natural law and its intuitionist overtone is his psychological hedonism. To be sure, a hedonistic motivation to morality cannot be denied in Locke. But it must be remembered that though he defines good and evil in terms of pleasure and gain, these are to him only consequences of a morally right action; they do not constitute its essence.
A moral law is eternal and universal and it is obligatory independently of its pleasurable consequences. “Utility”, says Locke “is not the basis of the law or the ground of obligation, but the consequence of obedience to it.” Locke’s moral theory, therefore, is essentially deontological rather than utilitarian and consequentiality.
In legal theory similarly he is more of an intellectualist than a voluntarist. There is, therefore, no conflict between natural law postulated in the Second Treatise and the ethical and epistemological theory of the Essay. Locke is a consistent Natural Law theorist.