The debate surrounding innate ideas is not a recent controversy in philosophy as opinions have been known to differ on whether the mind is born with innate knowledge, or whether knowledge is learned. Seventeenth century philosophers John Locke and Rene Descartes held conflicting views on the topic of innatism, with Locke arguing against the idea and Descartes supporting it. This essay will explore Locke’s main criticisms which include the argument of general consent, the argument from the use of reason and the argument concerning implicit knowledge, all of which will be compared to Descartes’ views. I will focus on the primary texts of Locke’s ‘An Essay Concerning Human Understanding’ (1996) and Descartes’ ‘Meditations of First Philosophy’ (1993), whilst making reference to other sources. I will evaluate both of the philosopher’s views to show that both theories have flaws. For example, Descartes’ requirement to believe in God and Locke’s heavy focus on empiricism, despite the problem of regularity. Due to this, I will conclude that whilst neither argument is fully convincing with their views on innate ideas, Descartes’ case is more convincing as the theory of having innate ideas is possible. Whilst Locke believes that God has created us for a certain purpose, he rejects the idea that theoretical nor ethical knowledge has been imprinted upon our minds from the outset. Taking an empiricist role, Locke describes this by imagining the mind as a blank slate, or tabula rasa, where man has no previous knowledge and all must be acquired through senses and experience. He sets out to use the “historical, plain method” (Locke, 1996, 316b) in order to discover “the original, certainty, and extent of human knowledge, together with the grounds and degrees of belief, opinion and assent.” (Locke, 1996, 316a) Descartes expresses an opposing view to Locke. The notion that certain ideas are inborn labels him as a rationalist and dates back to Plato’s writings. In his epistemological writings in the Meditations, Descartes attempts to discover what knowledge can be acquired. A key concept of Descartes’ philosophy is the cogito ergo sum, I am thinking therefore I exist. He uses this to support innate ideas as it is impossible to doubt one’s own existence and any thought in the mind is proof that one exists. The origins of the concepts brought up can be traced back to one’s nature, as Descartes’ claims that his “understanding of what a thing is, what truth is, and what thought is, seems to derive simply from my own nature.” (Descartes, 1993, pp. 37-8) Locke’s critique of innate ideas begins with the argument that there are no universal principles that mankind have collectively agreed upon. This is in response to the supporting premise that there are speculative and practical principles which are universally agreed upon from birth. Locke argues that in order for innate ideas to be factual, they must exist in the mind of every person. Since this is not the case, the concept of innate ideas has no logical grounds to be true. For example, a fundamental principle would be to refrain from telling lies, however there is no general agreement as some people feel comfortable in doing so. In addition, children do not recognise that they have to tell the truth, it is taught and experienced. This is discussed further in Locke’s writings in Book 1 of An Essay Concerning Human Understanding (1996). Locke argues his case using two examples of proposals where universal consent could be applied: “What is, is” and “it is impossible for the same thing to be and not to be.” He supports this with the claim that “it is evident, that all children and idiots have not the least apprehension or thought of them,” (Locke, 1996, I) implying that the previous concepts are not understood by everyone, therefore