Four years ago, the Internet was lit up by the color of the dress controversy? Was the dress blue and black, or was it white and gold? Everyone was firmly on one side or the other! This Internet sensation actually highlighted a debate that has been raging for hundreds of years in both philosophy and science: How much can we really know about the real world?

Step one in understanding this problem is to appreciate the nature of transducers. A transducer is anything that converts one form of energy into another. For example, a light bulb converts electrical energy into light; a thermostat converts heat into mechanical motion, which may then flick on a switch; Geiger counters convert radioactive radiation into audible sounds, and so on and so forth. Our senses are our own transducers, which convert one kind of energy into another. 

Since autumn is fast approaching, let’s imagine that we go apple-picking. It’s a glorious fall weekend and a row of trees proudly exhibits vibrantly red apples. We reach up, pluck an apple from the tree and hold it up in the sun. It is a magnificent red apple. What is happening right now? The answer is that our visual transducers are in play. 

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As we observe the apple, frequencies of light from the sun are hitting the apple. In high frequency light, the waves are close together; in low frequency light, they are far apart. The apple, due to its skin’s molecular consistency, absorbs most frequencies and reflects a certain kind back. When that particular light frequency hits our eyeball, it exposes the photoreceptors in our eye to a certain number of waves per second. Based on that, our optic nerve sends a signal to our brain. Our brain’s neurons, in turn, fire in a particular kind of way, sending signals along a few neural pathways, and eventually a “red” experience emerges. 

Our apple-picking example raises the question: is there actual redness in the physical world? The wavelengths aren’t red—they are just waves that are either spread out or pushed together in different ways. The frequency of light is not a color; it’s just a collection of waves. The apple skin’s molecular structure is not a color but merely a substance that absorbs certain frequencies of light and rejects others. The photoreceptors in the back of our eye aren’t red, and neither is the electrical signal sent along our optic nerve or our neurons. Finally, the neural configuration that produces the experience is not red either. So, does “red” actually exist?

The only thing that is “red” is our visual experience of the apple. The property of “redness” is a mental phenomenon, not a property of the real world. It is an experience produced by our mind, in response to stimuli from the world. The debate over the color of the dress is really a stunning illustration of how our brains process information. Author Marie Rogers calls it “a brilliant example of how breaking the perceptual system helps us learn more about how our brains work.” 

For philosophers, however, the dress example demonstrates much more, as it reopens the epistemological debate: how much can we ever really know about the real world? Once again, I refer to the transducer analysis, which can be applied not just to sight, but to all our senses as well. 
Our ability to hear sounds is dependent on the reception of sound waves and its transmission to, and reconfiguration by, our brains into actual sounds. The longstanding question—does a tree falling in the woods, with no one to hear it, make a sound—now becomes easier to solve. The falling tree does produce sound waves, but those waves are never “converted” into sounds unless a sentient being with a functioning transducer experiences it. 

How about taste? When we bite into an apple, chemical substances penetrate the surface cells of our taste buds, which respond in four basic molecular patterns: sweet, sour, salty or bitter. Regardless of the culinary skill of the most accomplished chef, that’s all that exists. Flavors do not reside in the substances we ingest, but rather are byproducts of our minds, which take the stimuli and produce our experience. 
Our sense of smell and our experience of touch are subject to similar analysis. Gaseous molecules permeate the lining of the olfactory membranes that cause our transducers to produce the experience of fragrance or odor or something in between. Stimulus of pressure, heat, cold, touch, and pain all rely on our brain to interpret and react to neural “information” provided to it by our sensory apparatus. This is why it is possible for neurosurgeons to surgically poke the brain of a patient, producing reactions that are identical to that person’s experience in the real world. 
But if we experience things so subjectively, can we really know much about the real world? Writer Court Holdgrafer thinks that we cannot. He likens our ability to see reality to the little boy who watches a baseball game through a knothole in a fence—all he can see is third base. He watches the entire game through that hole. For him, baseball is about some guy (the third baseman) standing around kicking the dirt and spitting all the time. Once in a while, another guy comes out of nowhere and slides into him. Not much of a game, he concludes, and hardly a national pastime! We too, claims Holdgrafer, possess only a knothole view of realty.

I humbly disagree. Our knowledge of reality is comprised of transducer-like responses of our mind to sensory data. Our “knowledge” is a complex enterprise, which is not given to the mind or poured into it, but rather something it manufactures. The finished product—our perceptions, concepts, ideas, beliefs, etc.—become our working hypothesis about the world around us. Every idea is, in reality, a subjective working model that enables us to handle real life events or objects with some degree of pragmatic efficiency. However, as intelligent beings, we are able to compare our responses to different stimuli and make conclusions about their legitimacy. That process is called science. The only reason science has been able to progress is that its analysis of what is real and what is not has made great strides over centuries. 

Even the dress question has been the target of scientific analysis. Science maintains that the brain uses visual reference points as it examines millions of observations. With that experience comes what is called color constancy. Coupled with contextual knowledge and a process called “top down” processing, our brains are able to produce our color experiences. The reason why “the dress” produces different results in different people is that the stimuli emanating from it are on the edge of our perceptual boundary. Which color we decide it possesses will depend on our brain’s particular calibration, which will vary from person to person. So, clearly the dress is blue and black, I mean, gold and white!

Either way, it was really a very nice dress, don’t you agree?