We have already, in a previous post (link here), considered whether, ontologically speaking, reality is objective or subjective in nature—that is, whether reality is an external “stubborn fact,” so to speak, or genuinely subordinate to the whims of perception—and so concluded that it must be objective, as the alternative has an inevitable recourse into logical absurdity. And from this conclusion we too examined whether some degree realism or absolute conventionalism ought to be held as true (that is, whether or not we can, at the very least in a limited way, understand how things are as they really are, or if all knowledge regarding the objective reality is merely an approximation or analogy of it); finding again that the alternative has an inevitable recourse into logical absurdity, it was decided that some degree of realism must be possible. So now we must endeavor to consider the degree to which we can understand reality as it really is—and this has two considerations within it: the first, the value of the senses in the pursuit of knowledge, and the second, the natural limit of human cognitive ability.
But before we consider these things, you may first be wondering what—if anything—this has to do with the Catholic faith.
Although there are many intersections between the aforementioned considerations and the beliefs of the Catholic Church, the most manifest is the existence of God, and that we can know of His existence through reason. That reality is objective shows that if God does exist, He exists for everyone, and there is no “He exists for me, but not for you.” And, in regards to the falsity of absolute conventionalism, we now have the beginnings of the bases on which we can prove that the He does or does not, because it shows that we can, at least in some degree, understand and make accurate deductions about reality. And again, now regarding the questions of human cognitive limits and the value of the senses in the attainment of knowledge, we are strengthening or weakening those bases, depending on which conclusions are shown true.
The First Question
So let us consider, then, the first of the two questions: whether the senses have any value in the attainment of knowledge, and, if they do, to how high of a degree?
To begin, we will consider two strong objections regarding the senses having very much value, the first being Plato’s , and the second being a modified form of Descartes’ .*
The first is as follows: if we cannot often tell the difference between our perceptions in dreams, which are falsities, and that which we claim to be reality when awake, while we are asleep, how can we say that what we perceive in our waking hours is any more reliable and true than our perceptions in dreams, since we hold it to be the truth only when we are awake, and something else to be the truth when asleep? More simply put, if during dreams we think our perceptions are true, we cannot hold that our perceptions while awake are of any more value on the basis that we think they are true.
The reply to this objection is as follows: Everything of which we dream originates from our waking perceptions, be it through the dream making use of composites (e.g. a dreamed Chimera which has the parts of a lion, a goat, and a snake—all of which we originally perceived in our waking hours), distortions (e.g. a lion with two faces, or a monster vaguely resembling many creatures but none too closely), or direct copies (e.g. having a friend being present in a dream). Hence, because dreams manifest only corruptions and copies of that which we perceive when awake, it therefore follows that dreams are reliant on our waking perceptions for their source material, and so dreams are not true perceptions or sensory experiences at all, but merely mental semblances of them, hence their little value in uncovering the truth. To put it in a summarized manner, because the contents of our dreams are things we perceived when awake, the contents of the dreams are not being truly perceived by the senses while dreaming (unless stimulated by a smell or some other stimulant, in which the case the presence of the smell or stimulant has been accurately conveyed by the senses to the mind and placed into the dream as a consequence to this true sensory perception), but recalled by the mind, and hence cannot be used as evidence against the reliability of the senses on the grounds that we hold dreams to be false despite the senses during them telling us otherwise—because dreams do not actually stimulate the senses, as demonstrated above.
And now to the second objection, which has been adapted from Descartes: It seems that all we experience may simply be a mental construct, due to there being a lacking of indications to the contrary, and our minds only being thus far proved to exist (i.e. cogito ego sum; I think, therefore I am). Hence, via Occam’s razer, it seems that we ought to only suppose the existence of the mind, considering all else to be imagined.
The reply being: If we grant that all perception is merely mental construct, it follows that we ought to be able to imagine that which has not yet been perceived (e.g. a new color) because such is really the same as receiving a new perception, but we cannot imagine that which has not yet been perceived in any capacity (e.g. a new color)—hence the above-mentioned limit to the contents of dreams—and so all perception is not then a mental construct, but the becoming aware of something that is external to the mind.
Now let us consider something logically weaker, the “Matrix” proposal, so called due to the film which popularized the concept. In this case, our senses our directly being substituted or deceived. If this is the case, the objection has implications only if we suppose the world outside of the simulation to have a differing set of rules and principles than within (which is not as is proposed in the film which is its namesake, generally speaking)—for if they are the same, our metaphysical reasonings about the simulation apply to the real world. So let us then assume the rules and principles differ. In this case, as with the other, the proposal, though unanswerable, is so due to its being an unfalsifiable hypothesis—having no more weight than the popular example of “there’s an invisible, intangible unicorn that floats above my head.” Can you prove it wrong? Well, no. What about proving it right? This too is impossible. And just as we dismiss the unicorn on the grounds of its equal indefensibility, we so too dismiss the Matrix.
Thus, the objections do not stand, and it seems that the senses do have some value in the attainment of knowledge.
But to what degree do they have value? Consider the existence of the so-called “self-evident” principles upon which the overwhelming majority (this majority is excluding some of those in a state of psychosis) agrees despite lack of collusion. We universally accept that stones are solid, and that the sun is hot, among many, many other such things; this being agreed upon by all peoples, regardless of cultural contact. These notions are so pervasive and held so strongly that on the rare occasion that one rejects these, they are held to be defective—be it mentally or sensationally, this seemingly being confirmed by those in psychosis being able to at times even recognize the psychosis of others. This suggests—perhaps even mandates—that each individual is receiving the same or similar sensory phenomena, and although how their minds may interpret and understand this sensory data may differ (for we cannot tell if red appears to be blue to another), we nonetheless are consistent in our discourses about the same things regarding these basic principles. It is for this reason that, even if we suppose that there is some difference in how our minds interpret sensory data, convention ensures that we share a common understanding, not of the matter of the things, which is the object of the senses, but—as Plato first suggested —of the forms, or the essences of those things (which Aristotle points out is any given thing’s function and capacity ), the essences being the objects of cognition (this being why, even if our understandings of the matter may differ, we will nevertheless recognize the same thing as the same thing when recounting its attributes to one another, because we comprehend its form, or function and capacity, through the perception and conventional descriptions of the matter).
Thus, the senses are of immense value in the attainment of knowledge, insofar as they allow us to comprehend the essences of things via their material attributes (this being why, when the essence of a thing is unclear, we do not recognize it by its corrupt matter, except for when, if the matter is not so corrupted that such is impossible, we recognize the object after having been informed of its proper essence or form).
The Second Question
Now we ask the following: what limit—if any—is there to human cognition? As it so far seems, there appears to be no limit to what man can comprehend in regards to the complex (that is, as far as there is some knowledge which can ultimately be derived from the senses regarding those complex things); with each passing year, more and more complex natural systems are becoming understood—if there is a point of complexity which truly lies beyond the reaches of the human mind, we don’t seem to have even spotted it in the distance. In regards to simplicity, however, the opposite is quite clearly the case. Consider the nature of the universal forces; whether considered things in and of themselves, or the interacting properties of things, they are mere brute facts—how are the forces this way and why? Suppose the multiverse solution is given: they are this way because it’s statistically necessary. Now the forces governing the multiverse are subject to this same question, and so this does not answer the challenge but simply pushes it one step farther back (not to mention, this solution does not solve the “how” of the original challenge). It appears that, when it comes to brute facts—the simplest, or least complex, pieces of knowledge—we are forced to rely on studying their effects in order to gain a shadowy semblance of an understanding of them (this too evidently being the case with God, the simplest and most prior of the causes).
Thus, there is clearly a limit to human understanding, this limit existing undoubtedly at least in simple things. And so as there are things beyond the limits of human cognition, the prophet Ben Sira tells us :
What is too sublime for you, do not seek…
what is hidden is not your concern.
*Descartes’ argument has been modified to further differentiate it from Plato’s, and in doing so give it more force in light of the prior refutation of Plato’s argument.
 Plat. Theaet. 158b-158e
 Descartes. Med I
 Plat. Theaet. 184-186
 Arist. Pol. I.2, 1253a23
 Ben Sira 3:21-22