<P> One of the most fundamental debates in philosophy concerns the "true" nature of the world--whether it is some ethereal plane of ideas or a reality of atomic particles and energy . Materialism posits a real' world out there,' as well as in and through us, that can be sensed--seen, heard, tasted, touched and felt, sometimes with prosthetic technologies corresponding to human sensing organs . (Materialists do not claim that human senses or even their prosthetics can, even when collected, sense the totality of the' universe'; simply that what they collectively cannot sense cannot in any way be known to us .) </P> <P> Materialists do not find this a useful way of thinking about the ontology and ontogeny of ideas, but we might say that from a materialist perspective pushed to a logical extreme communicable to an idealist (an "Away Team" perspective), ideas are ultimately reducible to a physically communicated, organically, socially and environmentally embedded' brain state' . While reflexive existence is not considered by materialists to be experienced on the atomic level, the individual's physical and mental experiences are ultimately reducible to the unique tripartite combination of environmentally determined, genetically determined, and randomly determined interactions of firing neurons and atomic collisions . </P> <P> As a correlative, the only thing that dreams and hallucinations prove are that some neurons can reorganize and' clean house' ' on break' (often reforming according to emergent, prominent, or uncanny cultural themes), misfire, and malfunction . But for materialists, ideas have no primary reality as essences separate from our physical existence . From a materialist "Home Team" perspective, ideas are also social (rather than purely biological), and formed and transmitted and modified through the interactions between social organisms and their social and physical environments . This materialist perspective informs scientific methodology, insofar as that methodology assumes that humans have no access to omniscience and that therefore human knowledge is an ongoing, collective enterprise that is best produced via scientific and logical conventions adjusted specifically for material human capacities and limitations . </P> <P> Modern Idealists, on the other hand, believe that the mind and its thoughts are the only true things that exist . This is the reverse of what is sometimes called classical idealism or, somewhat confusingly, Platonic idealism due to the influence of Plato's Theory of Forms (εἶδος eidos or ἰδέα idea) which were not products of our thinking . The material world is ephemeral, but a perfect triangle or "beauty" is eternal . Religious thinking tends to be some form of idealism, as God usually becomes the highest ideal (such as Neoplatonism). On this scale, solipsism can be classed as idealism . Thoughts and concepts are all that exist, and furthermore, only the solipsist's own thoughts and consciousness exist . The so - called "reality" is nothing more than an idea that the solipsist has (perhaps unconsciously) created . </P>

T is the philosopher who believe in that one can know only what comes from the senses and experience