In philosophy, ideas are usually construed as mental representational images of some object. Ideas can also be abstract concepts that do not present as mental images. Many philosophers have considered ideas to be a fundamental ontological category of being. The capacity to create and understand the meaning of ideas is considered to be an essential and defining feature of human beings. In a popular sense, an idea arises in a reflexive, spontaneous manner, even without thinking or serious reflection, for example, when we talk about the idea of a person or a place. A new or original idea can often lead to innovation.
One view on the nature of ideas is that there exist some ideas (called innate ideas) which are so general and abstract that they could not have arisen as a representation of any object of our perception, but rather were in some sense always present. These are distinguished from adventitious ideas which are images or concepts which are accompanied by the judgment that they are caused or occasioned by an external object.
Another view holds that we only discover ideas in the same way that we discover the real world, from personal experiences. The view that humans acquire all or almost all their behavioral traits from nurture (life experiences) is known as tabula rasa ("blank slate"). Most of the confusions in the way ideas arise at least in part from the use of the term "idea" to cover both the representation percept and the object of conceptual thought. This can be illustrated in terms of the doctrines of innate ideas, "concrete ideas versus abstract ideas", as well as "simple ideas versus complex ideas".