As a consequence, a piece of metal might count as gold for one person and not for another. See also *Secondary Qualities*.“Rationalism” is a collective name given to several philosophical systems marked by similar strains.
Rationalists tend to believe that reason is extremely powerful, and that by using it we can come to know almost everything that there is to know. According to Locke the real essence of an object is the object’s microstructure of corpuscles, which gives rise to the observable properties.
Gaining immense popularity in the 17th century, this movement sought to replace the messy and complicated *Scholastic* model of the world with a simpler picture.
According to the mechanistic view, all explanation can be given in terms of the principles of matter and motion.
The most famous Rationalists are Rene Descartes, Baruch Spinoza, and G. Although these microstructures do exist out in the world, real essences do not generate natural kinds the way the *Scholastics* and Descartes thought that essences did.
This distinction arises because Locke held that the determination of what part of the microstructure is included in a thing’s real essence is based wholly on the man- made *nominal essence*.A abstract general ideas are the pieces of our mental geography that correspond to our general terms, such as “man” and “cat”, as opposed to “Socrates” and “Garfield”.Our general terms refer to these abstract general ideas rather than to anything in the world.Locke believed strongly in this view of reality, and it had a powerful influence on the ideas he expounds in his Essay.Demonstration is the middle grade of knowledge according to Locke, not as good as *Intuition* but still a legitimate form of knowledge.Locke identifies abstract general ideas with what the *Scholastics* and *Cartesians* would call *essence*.In an argument from parsimony, the conclusion rests on the suppressed premise that it is best to posit as few existents in the world as possible.Intuitive knowledge is much the same thing as what later philosophers would call analytic truths. For Locke, a mode is something that depends on substances for its existence, something that cannot exist independently.According to Descartes, a mode was a way of being a certain substance (e.g. Properties such as square and red are modes for Locke, but so are numbers, and more abstract concepts such as “gratitude”, “beauty”, and “hour”.Demonstration is knowledge that proceeds by reasoning out a proof. An important concept in *Scholastic* philosophy, an essence was supposed to be the quality that made something the type of thing that it was.Each step of the proof in demonstration must be an intuition, so demonstrative knowledge depends upon intuitive knowledge.“Empiricism” is a collective name given to a variety of philosophical doctrines concerned with human knowledge. The essence of man, for example, was believed to be rational thought because it is rational thought that distinguishes man from all other beings.