should not be confused with Idealism, as presented by philosophers such as George Berkeley: as Platonic abstractions are not spatial, temporal, or mental, they are not compatible with the latter Idealism's emphasis on mental existence. Plato's Forms include numbers and geometrical figures, making them a theory of mathematical realism; they also include the Form of the Good, making them in addition a theory of ethical realism. Aristotelian realism is the view that the existence of universals is dependent on the particulars that exemplify them. Medieval philosophy Medieval realism developed out of debates over the problem of universals. Universals are terms or properties that can be applied to many things, such as "red", "beauty", "five", or "dog". Realism (also known as exaggerated realism) in this context, contrasted with conceptualism and nominalism, holds that such universals really exist, independently and somehow prior to the world. Moderate realism holds that they exist, but only insofar as they are instantiated in specific things; they do not exist separately from the specific thing. Conceptualism holds that they exist, but only in the mind, while nominalism holds that universals do not "exist" at all but are no more than words (flatus vocis) that describe specific objects. Proponents of moderate realism included Thomas Aquinas, Bonaventure, and Duns Scotus (cf. Scotist realism). Early modern philosophy In early modern philosophy, Scottish Common Sense Realism was a school of philosophy that sought to defend naive realism against philosophical paradox and scepticism, arguing that matters of common sense are within the reach of common understanding and that common-sense beliefs even govern the lives and thoughts of those who hold non-commonsensical beliefs. It originated in the ideas of the most prominent members of the Scottish School of Common Sense, Thomas Reid, Adam Ferguson and Dugald Stewart, during the 18th century Scottish Enlightenment and flourished in the late 18th and early 19th centuries in Scotland and America. The roots of Scottish Common Sense Realism can be found in responses to such philosophers as John Locke, George Berkeley, and David Hume. The approach was a response to the "ideal system" that began with Descartes' concept of the limitations of sense experience and led Locke and Hume to a skepticism that called religion and the evidence of the senses equally into question. The common sense realists found skepticism to be absurd and so contrary to common experience that it had to be rejected. They taught