Though I do indeed by necessity live as if some of the things I doubt about the external world are true, I will examine what I can legitimately know about the subject. I want to show in this post what can be known with absolute certainty about the external material world. I will clarify here that there are immaterial realities like logic and truth which would exist even if no material world did, and they are external to my mind and not dependent on its existence or awareness for their own existence. Logic and truth are not parts of the natural material world; they apply to it by pure necessity, but they are objectively ontologically different than physical matter (and my own mind) [1]. In this post, when I use the phrase "external world" I am speaking of the external material world: that which is composed of physical matter that exists outside of my mind, which is my consciousness.
I have a mind.
I think and perceive, and this is how I know that I exist. The existence of my mind is, alongside things like first principles, immediately obvious by experience and logic--self-evident (something is self-evident if it cannot be false and a denial of it brings contradiction), as I must exist to even doubt if I exist. I cannot be mistaken about the contents of my mind, including my beliefs, memories, and sensory perceptions [2]. I did not say that all of my memories of events and sensory perceptions have to conform to reality by logical necessity--but it is impossible for me to be deceived about the actual content within my mind. If I experience mental sensations of love or distress or sadness, it is infallibly true that I really am at that moment in a mental state of love, distress, or sadness. I know with absolute certainty that I really do have thoughts, doubts, memories, longings, fears, and hopes. Even if my best friend does not actually exist, I know with absolute certainty that my love for her truly does. Even if I was created five minutes ago with an elaborate set of memories of events that never actually happened, I know with absolute certainty that I really do have the memories within my mind. As you can hopefully see, introspection and consciousness cannot be illusions in any way [3].
But I am not merely a mind: I am a corporeal being as well as a conscious one, as I will demonstrate. It must be noted that I do not need to prove that I have a body to prove to myself that something exists outside of me--logic and truth, which exist by inescapable necessity, are immaterial, but they do both exist independently of my own mind (they would exist even if I did not) and even independently of my awareness of them (they would exist even if I had no knowledge of them whatsoever). Solipsism--the belief either that nothing exists other than my mind or that I can know nothing for sure except for my own mind--is utterly impossible.
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| Introspection, the practice of searching one's own mind, is a major source of knowledge, although humans are not merely unembodied minds. Alongside logic, introspection is one of few avenues to knowledge which can provide absolute certainty. |
I have a body.
I experience physical sensations like temperature, pain, and contact with other objects, which I would be entirely incapable of experiencing if I were only an immaterial mind with no physical body at all.
1. A purely immaterial being cannot experience physical sensations.
2. I experience physical sensations.
3. Therefore I am not a purely immaterial being.
4. A being that is not purely immaterial has a physical body of some sort.
5. Therefore I have a physical body of some sort.
I do not need to know if how I perceive my body to appear is its actual appearance to know with infallible certainty that I do have a body. Perhaps in actuality I am just a brain in a vat or I have six arms or no legs. But it remains inescapably logically true that I do possess an actual physical body of some kind. Descartes, when in his period of intense sensory skepticism, concluded for a time that he did not know if he had any body at all, and yet it is impossible for his evil demon or any other being or thing to deceive me into having false physical sensations unless I have at least one actual physical nerve or organ to experience the illusory sensations (I do not mean that the sensations themselves are illusions, but that they do not represent actual external reality). This means that there is something material outside of my mind that serves as a physical, corporeal extension of my own being. Idealism, the belief that there is no such thing as matter, is just as mistaken as naturalism, the belief that nothing exists which is not a physical and material thing.
I have senses.
I am processing something with my senses. Whether or not I am experiencing actual sensory stimuli and perceptions is not up for legitimate internal debate, as I know for sure that I truly am perceiving things. It is impossible for my senses to be either reliable or unreliable unless they exist--and I know with absolute certainty that they do. Knowledge of this fact, which is absolutely certain, involves both internal awareness of my mind and the functioning of my senses. My senses feed me the information they process and then reason, which my mind grasps, renders my perceptions intelligible and enables me to think critically about them. The existence of my senses and my body are beyond all legitimate doubt [4].
There is an external world.
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| Knowledge of the external world is very limited, but not totally nonexistent. |
The fact that I have some kind of body proves to me that something material (other than immaterial things like logic and truth) objectively exists outside of my mind. My senses, which are housed in my body, inform me of an external world that they perceive. Something is outside of me, as my senses tell me; they are indeed contacting actual stimuli. I may not know the actual appearance or texture of what I am contacting, yet I know for sure that I am contacting something. Experience, not a priori reasoning (reasoning that can occur without sensory experiences), informs me of this.
Below I will address several important issues related to the external world.
--The Simulation Hypothesis
Speculation about whether I am a brain in a vat or in the matrix does nothing to affect the reality that there is something material external to my body. If any such scenario is true to reality, then an external world still exists, and at most it just has a different appearance and different physics than what I am perceiving.
--Object Permanence
Object permanence is a phenomenon where objects in the external world remain where and as they are unless acted upon by other forces. Someone who believes in it believes that if he or she leaves, say, a tablet computer on a particular table, the tablet will remain in that very spot unless moved by nature (perhaps a strong wind or a flood) or some being. A believer in object permanence would believe that the tablet, the table, and the room do exist fixedly and will not vanish just because he or she is not looking at them or feeling them.
This is not something I can prove to be true by logical necessity, but I know for sure that practically all of my recalled experiences reinforce the extremely strong perception that object permanence is indeed a real phenomenon. I do indeed act as if object permanence is true! Still, the fact that my body confines me to a particular area of space at any given time and that my senses are themselves limited (for example, my sense of sight only perceives things in front of me) do prohibit me from actually proving to myself with absolute certainty that object permanence is real, although I still have absolute certainty that I have senses and a body and actual knowledge that something material is indeed outside of my body.
--Other Minds
I know with infallible certainty that I have the strong perception that other humans which share my appearance and functions do really exist outside of my own body. They even seem to have consciousness. But, since I am neither omniscient (all-knowing) nor a telepath (a being capable of reading the minds of other conscious beings), I only know that I perceive these beings to have the same ability to reason and perceive that I do. The perception that other sentient beings with physical bodies exist outside of myself could be a mere illusion, as I can see only their bodies and my own consciousness, not theirs. It does not follow that just because they seem to be conscious that they actually are.
--A Finite Beginning
The external world must have a beginning, as it is impossible for there to be an infinite number of past events, moments of time, and cause and effect relationships before the present time. Infinite regress, an infinite series of preceding events, is impossible. If infinite regress did exist, the present could never be reached--and anyone who denied that the present moment exists and has objectively been reached denies something that is self-evident (meaning that denial of this brings one into contradiction). The past has existed for at least a moment, but the duration of the past is irrelevant to the truth of what I am demonstrating here. A finite past means that time and events in the material world had an absolute beginning, and something cannot begin to exist without a cause (nothing can produce anything). Since self-creation (something can't create itself because it would have to exist before it existed to do so), beginning to exist without a cause, and infinite regress are impossible, something has always existed without a beginning and created the material world. This thing is called the uncaused cause. If one assigns the title of God to the uncaused cause, then belief in the existence of God is not a matter of mere faith and is a belief which reason demonstrates cannot be false.
And thus I have reached the end of a summary of what I know for sure about the external material world. Despite much reflection, a multitude of questions remain about the external world which I cannot honestly answer due to my epistemological limitations. I do not enjoy my inability to answer them. I take no pleasure and derive no sense of excitement from my ignorance on such matters, yet, although this commitment has brought much mental discomfort to myself, I am committed to truth and reason and not what I am told by others or want to be true. Still, I have some knowledge of the external world. It is not as if the only absolute certainty I can have is of the existence of my own mind or of abstract logical truths.
Summary of observations:
1. My mind--my consciousness--exists, and I have absolute certainty of its existence and contents.
2. I have a body, as without one I wold be incapable of experiencing physical sensations, which I consciously experience constantly except for when I sleep. Though the appearance of my body is uncertain, I have absolute certainty that I do have a body.
3. I have senses through which I have perceptions of the external world that by necessity are either true or false. As with the existence of my mind and body, I have absolute certain of this objective fact.
4. Although I cannot verify or falsify things like the simulation hypothesis or object permanence, I am indeed contacting an actual external world, which exists outside of my body and which must by logical necessity have a beginning and therefore a cause.
[1]. https://thechristianrationalist.blogspot.com/2017/07/a-refutation-of-naturalism.html
[2]. Here, I distinguish between experiences of mine which are fallible and those which are infallible. By fallible experiences I mean experiences which could amount to mere perceptions that do not conform to objective reality and by infallible experiences I refer to experiences which must by absolute necessity actually tell me about the way objective reality is. See here:
https://thechristianrationalist.blogspot.com/2017/07/the-reliability-of-experience.html
[3]. https://thechristianrationalist.blogspot.com/2017/07/aspects-of-consciousness.html
[4]. https://thechristianrationalist.blogspot.com/2017/04/the-reliability-of-senses.html
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