All conscious beings are conscious of something. We perceive. Right now, reading this post, you are perceiving the screen, the words, and the meaning that you derive from those words.
We trust that what we perceive is precisely what is actually “out there” in the “real world” (i.e. reality). We trust our senses and our perceptions to be a correct portrayal of “reality”. We do this, despite having full knowledge of a wide range of variance in how we and other people perceive “reality”. We can have differing views from others on what is hot, cold, blue, red, grey. We can even have variance in our own views. When we are sick our sense of taste is different. Try drinking orange juice after brushing your teeth. It tastes metallic! When you are in a different mood, things appear differently. When you are starving, food tastes better.
So what does that mean? Is the taste of orange juice “in” the orange juice? Is the taste of orange juice a property of the orange juice? Most people would probably say so. But how can that be? The orange juice didn’t change between when I was thirsty, when I was sick, or after I brushed my teeth. Why is the perceived taste not constant?
We inherently know that our own states can alter how we perceive things through our senses. And so, with a scientific world view of atoms and mechanisms, we can say that each state is different in some causal way. The toothpaste on my tongue altered how I taste the orange juice. But really, truly, the REAL taste of the orange juice is still there. I just didn’t accurately experience it. That is probably a common interpretation.
There are other examples of differing perception. Color blindness. Synesthesia (where people mix up senses, i.e. they smell colors, taste sound, etc). Now, with all this variance, whether it is color blindness, synesthesia or the difference between orange juice with or without brushed teeth, under what criteria are we to judge is the “actual”, the “true”, the “normal” the “REAL” taste of orange juice, the real phenomena in question? Aside from convention, I am not so sure.
And so, if that is the case, is reality just something we agree upon?
We believe that our everyday normal waking experience of the objects we perceive is the true reality of things. And those other examples, color blindness, synesthesia, brushed teeth, etc, all of those states are abnormal. Those are the special cases. But really, truly, our “normal” waking state is the truth of reality. I won’t comment on this view point, but needless to stay it is not a good argument.
A scientific hypothesis could be made that under the assumption of evolution the organisms that are best able to perceive nature/reality as it truly is will be better at surviving. This is a valid hypothesis. But it opens the door to a counter hypothesis along the same lines. It is perfectly conceivable as well that perceiving things truly as they are might be a detriment to the survival of an organism. Why else could denial come into existence? It is better to deny the existence of something, some experience or some truth, for ones mental sake (which is important for survival and success) than to address it as a reality. There certainly are scenarios where ignorance is much more important to survival and success than absolute knowledge.
In addition to this counter hypothesis there is a possible scientific rationale for skepticism, for being skeptical that what we perceive is actually fully true of how things really are.
We model ourselves through science and scientific theories. Under this model the body is made up of cells, cells are simply molecules, molecules are just atoms. These atoms, molecules and all the operations that occur in the body operate under forces (electrochemical, etc) and are governed by the laws of physics. Now, we also operate under the view that our perception is a physical process. The orange juice hits my tongue. It physically touches it. This physical interaction is nothing more than atoms touching other atoms. The taste buds (physical receptors on my tongue that bind molecules in the orange juice, that is, molecules OF orange juice) once activated play a game of dominoes with other atoms, a cellular process called a signalling cascade. The orange juice touches the taste bud, that taste bud (molecules) interact with another molecule, and that with another, and another, and another until molecules in your nerves reach molecules in your brain, and somehow, the experience of taste is perceived.
Now, someone who might have a “defective” taste bud (i.e. a genetic mutation that causes the tongue cells to express a different orange juice receptor) such that there sense of taste might differ from what everyone else tastes. For that person, they might always taste orange juice as if they brushed their teeth. Or maybe they taste something completely different. We believe that the reason why people differ in their perceptions have a physical causal reason.
Here is the thought experiment: It is perfectly plausible that there might actually be a single objective truth to what orange juice tastes like. Let’s just assume this. If this were the case, then in order to perceive it, there must be a perfectly tuned machine (the human body and all the machinery, i.e. molecules) capable of tasting the orange juice as it is. But, it is perfectly plausible that in order for the orange juice to be perceived EXACTLY as it truly is in reality, the machinery involved (the molecules and biochemical structures of the cell) are not stable or possible under the laws of physics. It is quite possible that yes, there is a single true objective taste to how orange juice actually is, but if there is, it can only be experienced as such under specific physical conditions. And it is perfectly plausible that those physical conditions are simply not stable under our laws of physics, or via the machinery of the human body (carbon based organic chemistry), etc.
If this is the case, there is a scientific rationale for skepticism. It would be impossible to know if it was the case or not.
So what does that mean? You tell me.