Can We Know Anything for Sure?

written by Dr. Doug Potter

The following is an excerpt for our Why Trust the God of the Bible? ebook.

Many today fail to see the importance of grounding their reasoning process in reality in spite of the fact that whatever is not based on reality is un-reality, in other words unreal. The slippery slope of subjectivism and relativism is the result of such “reasoning” manufactured in the imaginations of the mind rather than in reality, on Truth. This distinction is especially important for Christians who desire to share their reasonable faith. Sadly, subjectivism has crept its way into the church with the assumption that we do not need to defend our faith with reason; we only need the Bible.

Despite the claims of subjectivism and “blind” faith, one of the most fundamental observations anyone can make of physical reality is that it changes, and yet something about it remains the same. This observation is the first step in a complete apologetic for Christianity. What remains the same in this physical piece of reality is its essence. What changes are called accidental properties. We can observe anything in reality, natural or man-made, for example a real tree, and see that it changes over time—grows larger, develops branches, colorful leaves, etc.—and yet it remains the same tree such that it is distinguishable from all the other trees. Its change is accounted for by the principles of actuality (act) and potentiality (potency) that are present in all created things. Actuality is the existence of some thing. Potentiality accounts for the capacity of some thing to change or become other than what it is. Change could be substantial, in that I could destroy the tree and it could no longer exist. Or it could be accidental, such as cutting off a limb. The change could be internal, such as its growing a new limb, or the change could be external if I cut the tree down.

Everything in the world that we experience is a composition of form (actuality)—or what something is—and matter (potentiality to change) that individuates the form to be this thing and not that thing. For example, a cat is a cat because of its form or catness (what it is), and its matter individuates it to be this cat as opposed to that cat. Matter, as used here, should not be equated with physical matter, and form should not be equated with the shape of something. Instead, these are principles found in things or substances. As already explained, there are things essential and accidental to a particular substance. Something essential cannot be removed without changing what it is. Something accidental could be otherwise and would not change what something is. For example, it is essential to the nature of a cat that it be an animal nature. If that is changed or removed somehow, it ceases to be a cat. But it is accidental if the size and color of the cat change. Despite the change, it stays a cat. Such a description is possible for every created thing from the smallest subatomic particle to the largest galaxies.

We come to know reality in an act of existence, in other words by its actual existence. This knowing relates to its form (essence) and its matter (potential to change). The form of something is related to its actuality. Again, form is what something is (i.e., an essence). For example, a cat has the form of catness, and a dog has the form of dogness. Matter is related to the individual potentiality (to change). It is that which individuates an essence to be this cat or that cat. The form of a substance is immaterial. The matter of a substance is what individuates the essence to be a particular thing that gives it extension in space, which is limited to its form. We can say a dog is not a cat because of their different form or essence. We can say this cat is not that cat because of their different matter or individuation of matter.

The Process of Knowing

The soul is the substantial form of the human body. The way in which we know something is by its form, which is united to matter. We know things via our five senses. Since the form of a substance is immaterial, it is able to enter our mind, and we are able to know the thing, know the form extracted (in our mind) from its matter, as it is in itself. Contrary to what some philosophers have proposed throughout history, the form that enters the mind is not a different substance or copy of the substance that comes to exist in the mind of the knower. Rather, the same form that is united with matter unites with the mind of the knower; in a sense the knower and the thing known become one. 

Once the form enters our minds, in an act of existence, our internal senses combine all the available external sensitive input. Our intellect is able to extract the universal catness, for example, from the particular cat. We are able to form mental images (phantasms) of particulars by using the internal senses combined with other intellective powers such as remembrance and the abstracted universal. We are able to make judgments and form concepts and ideas about the known thing. All of this and much more happens effortlessly, almost without awareness.

This process of knowing can be applied to sensible reality and to the interpretation of any text or spoken word. We come to know a written or spoken word the same way we come to know any other thing in sensible reality. First, the author or speaker has an idea. Meaning exists as form (immaterially) in the mind of the author/speaker. The author/speaker causes a text to exist by imposing form (meaning) upon language (combining it with matter) to create a text or spoken word in sensible reality. The speaker expresses his thought, then the mind of the reader or hearer extracts the form (meaning) from the text or spoken word in reality through the senses, and then the meaning is processed by the intellect. In this way a reader or hearer is able to know the meaning that is in the text or spoken words.¹

Why is This Important?

All humans have the same nature/essence; therefore, all human intellects have the same basic capacities. Since the forms in reality are the same as what comes to exist in the human mind, what something is is determined by reality and not the knower. This is what we mean by truth. Truth is that which corresponds to its object, or, more specifically, truth is the conforming of the intellect to reality. Knowledge, meaning, and the intended purpose of all things are grounded in reality and are objectively verifiable. This explanation supports all human endeavors in the sciences and humanities and particularly makes Christian apologetics, theology, and ethics worthy endeavors.

This unity of existence between intellect and reality is the basis for the two extremely important great apologetic goals: to demonstrate the existence of God and to demonstrate the historical truth that God raised Jesus of Nazareth from the dead.

1. For a fuller treatment of epistemology, consider Frederick Wilhelmsen’s Man’s Knowledge of Reality: An Introduction to Thomistic Epistemology (Upper Saddle River, NJ: Prentice-Hall, 1956).

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