"Unfortunately, many people, including many scientists are not aware of the fact that modern science is full of theoretical entities, like gravity, quarks, positive charges, negative charges, electromagnetic waves, energy, and so on. These people assume that quarks exist the same way that rocks exist, and will summarily dismiss as absurd any theoretical entity proposed by alternative conceptual frameworks.
As an example, shamans the world over use the concept of nature spirits to explain certain phenomena. People unaware of the difference between perceptual entities and theoretical entities will often dismiss the idea of spirits on the basis that 'Western science has searched far and wide and never discovered any nature spirits.'
The problem here is that nature spirits are theoretical entities. You don't confirm or disconfirm their existence by rummaging around the forest, just as you can't confirm or disconfirm the existence of gravity by looking for it in the English countryside.
Suppose I said: 'Well, at long last I have proven that gravity doesn't exist since I have searched far and wide, near and deep, and I haven't seen any gravity anywhere.' [Substitute energy for gravity with the same result.] Do you think the physicist would accept my refutation? Or course not. Yet he turns and believes that he can refute theoretical entities proposed in other knowledge systems by the same device.
You don't discover theoretical entities, you invent the concepts as part of an attempt to explain the perceived activities of phenomena. You don't confirm the existence of theoretical entities by direct perception, you confirm their existence by observing and interpreting the activities of phenomena generated by experiments conducted in the context of the conceptual framework to which the theoretical entities belong.
That last sentence means: The concept of gravity is meaningless outside the context of the conceptual framework (Western science) to which it belongs; and the concept of nature spirits is meaningless outside the context of the conceptual framework (shamanism) to which it belongs."
Entire Blog Post: http://donmatesz.blogspot.com/2011/04/epistemology-percepts-concepts-and.html