The Reliability Of The Senses

Are our sensory perceptions reliable?  Many people
seem to merely assume that their senses are reliably
informing them of the way external objects really are.

 

Can we trust our senses?  How can we discern if our senses deceive us or not?  What ramifications follow from the truth of the matter either way?  Every day I rely on my senses to inform me of things like my position in a room, the distance between me and other objects, and other information.  These questions clearly address a very important issue.  We use our senses constantly when not asleep, forced to use them simply by our very nature.  Here I will detail several truths about the senses.

As I proved in a post on the reliability of memory [1], it is impossible for my memory to be unreliable unless I have a memory to begin with.  In the same way, my senses cannot deceive me unless I have senses; the recognition of this foundational truth forms the logical starting point for all knowledge about my senses and the perceptions of stimuli (things that stimulate sensory responses) that they receive.  Anyone contemplating the reliability of the senses must begin with this knowledge.  As for the definition of what qualifies as a sense, when I use the word I am referring to something that allows me to perceive external stimuli.

Even if we have distorted senses, it remains objectively
true that we have actual sensory perceptions.

With that point addressed, one of the next major points that follows is that I have no reason to suppose that my senses are totally inaccurate in how they perceive the external world.  No one can demonstrate that they possess total reliability, and one can demonstrate that sometimes they do deceive me, but no sound argument for the total unreliability of my senses exists.  Whether such an argument would take the form of an argument for the simulation hypothesis or not, no one can appeal to a legitimate argument of this type because there isn't one to appeal to.

Now, I indubitably know on a constant basis that I am indeed actually feeling, seeing, and hearing things.  No way exists for this fact to be an illusion manufactured by an external source; I know with absolute, infallible certainty that I do perceive some things on a regular basis with my senses of sight, hearing, and feeling (touch).  The most direct of experiences confirms this to me all the time.  The only legitimate skepticism about these perceptions has to do with whether or not they conform to reality, not whether or not the actual perceptions or stimuli exist!  This directly contradicts the claim of an infamous philosophy called solipsism.  Ontological solipsism posits that nothing exists outside of the mind of the self, so if I were a solipsist, I would believe that nothing at all exists outside of my own mind.  But logic exists outside of my mind.  To deny the existence or reliability of logic is to affirm both at the same time [2], and thus logic--a series of self-evident, self-verifying immaterial laws that are immaterial and inescapably exist by necessity--exists outside of myself, meaning that ontological solipsism is utterly impossible.

Solipsism, the belief that nothing exists outside of one's own
mind, is logically impossible.

Unless I momentarily jump into the air or leap off of a tall object, I constantly contact something outside of myself and have awareness of this as long as I do not sleep.  Interestingly, every argument for skepticism about our perceptions of the external world inescapably involve an idea of the external world themselves.  Descartes' evil demon hypothesis, the brain in a vat scenario, the Matrix, and any other non-solipsistic ideas about reality (remember, solipsism is impossible) still incorporate an external world, meaning that regardless of whether or not my specific sensory perceptions (i.e. I am holding my iPad to type this) conform to the external world, an objective external world still exists.  If Descartes' demon deceives me then the demon and the material world still exist; if I am a brain in a vat being stimulated by a scientist to perceive certain images and experiences then a scientist, a vat, equipment, and the rest of the material world still exist; if I am in the Matrix as sentient robots rob me of my energy then robots and the material world still exist, and so on.

As an aside, although it is seemingly a popular belief that humans have five senses, in reality humans possess at least 10 distinct senses.  The traditional five senses exist alongside at least several others, which are called proprioception (sense of position), equilibrioception (sense of balance), nociception (sense of pain), thermoception (sense of temperature), and chronoception (sense of time).  Some of these senses may seem like they are just subcategories of the traditional five, but a closer examination reveals that they are indeed distinct senses of their own [3].

In the end I still cannot fully verify that my senses perceive correctly, only that they perceive.  But that is all I need to know for sure to live my life!  As I explained in my post Brain In A Vat: Reality Remains Unchanged [4], the possible existence of some sensory simulation that could engulf me even as I write these words changes nothing about ultimate reality.  At the absolute worst, there is simply another layer between me and the objective external world, I still stand responsible for all of my decisions, will still bear the consequences of my worldview, and can still use logic to prove certain truths to myself.  At some point I will collide with the truth one way or the other, but reality remains unaffected by any faulty perceptions of mine.

The question of the reliability of the senses poses an epistemological problem, not an ontological one.  Nothing about ultimate reality changes even if our senses were to constantly deceive us!  With that in mind we can afford ourselves some security about the state of our knowledge pertaining to the senses.  After all, both our lives and objective reality will still continue onward either way.


Summary of observations:
1. I have senses, whether or not they are reliable.
2. I have no reason to think my senses are totally unreliable.
3. Even if something is manipulating or deceiving my senses, I still know that my senses are processing stimuli; I know for sure that they are contacting and interpreting something.
4. I cannot know if my senses are perceiving the external world as it truly is.
5. Objective reality remains unchanged by any potential unreliability of my senses.

 

 

[1].  http://thechristianrationalist.blogspot.com/2017/03/the-reliability-of-memory.html

[2].  http://thechristianrationalist.blogspot.com/2016/10/the-self-evidence-of-logic.html

[3].  https://thechristianrationalist.blogspot.com/2017/07/more-than-five-senses.html

[4].  http://thechristianrationalist.blogspot.com/2017/02/brain-in-vat-reality-remains-unchanged.html