Radical Skepticism (Part 2 of 4)

APOLOGIA
By Hendrik van der Breggen
The Carillon, September 23, 2010

Radical Skepticism, Part 2 of 4: Sensory Skepticism

Radical skepticism concerning the external world is the philosophical view that we cannot have accurate knowledge about the physical reality that exists outside our minds. If radical skepticism were true, then we could not know the external world. Moreover, we could not know the external world's revelation of God, whether God's revelation is via the heavens declaring His glory or via Scripture's pages presenting reports of empirical evidence about Jesus Christ.

Should we be persuaded by radical skepticism? I think not.

There are at least four types of radical skepticism. Last time we looked at funky/pop skepticism. Today we will look at sensory skepticism.

Sensory skepticism tells us that we cannot know the external world because our senses deceive us. (This species of skepticism, like the dream hypothesis discussed in my previous column, is inspired by the philosopher René Descartes [1596–1650].)

To understand the force of sensory skepticism, consider the following examples. While rowing my boat, I put an oar into the water, but then the oar appears bent. While walking in the countryside, I see a flat wall on a distant farm building, but as I get closer the wall turns out to be curved. While strolling along railroad tracks, I see that the metal rails look straight and parallel to each other, but then on the horizon they appear to meet. While driving my car on a hot summer day, I see water on the road ahead, but as I continue to drive I observe that the road is dry. While volunteering as a lab rat for a psychology researcher, I see a red six of hearts as the researcher flashes a playing card, but later the researcher reveals that it was a red six of spades.

Clearly, my senses do deceive me. Therefore (or so the argument goes), my senses should not be trusted.

There are three reasonable criticisms that can be set out against radical sensory skepticism.

First, always does not follow logically from sometimes. The fact that we are sometimes deceived by our senses does not mean that we are always deceived by them.

Second, to know that our senses sometimes deceive us requires that they sometimes or often do not. Indeed, for us to discern that I mistakenly think that the oar is bent, that the wall is flat, that the tracks do not remain parallel, that the road is wet, or that the card is a red six of hearts requires that we have clear and accurate sensory knowledge. It presupposes that we know—accurately—that the oar is in fact straight, that the wall is in fact curved, that the tracks are in fact parallel, that the road is in fact dry, that the card is in fact a red six of spades. The argument of the sensory skeptic, then, requires as legitimate and true what it purports to show is not legitimate and true. It self-refutes.

Third, because the argument for sensory skepticism very apparently fails, our senses’ prima facie veridicality—that is, their very apparent truthfulness—remains. In other words, the burden of proof belongs to those who deny the obvious, so the senses are innocent until proven guilty.

It is reasonable, therefore, to go with what our senses tell us about the world, as long as we have no overriding reason to doubt them, and as long as we are careful.

How does this relate to Christianity? Significantly, it turns out that the reports concerning Jesus' resurrection tell us that the witnesses carefully used their senses to ground their belief. According to the New Testament record, the witness testimony has do with that "which we have heard, which we have seen with our eyes, which we looked upon and have touched with our hands" (1 John 1:1). Also, this record tells us that the resurrected Jesus appeared to individuals and variously sized groups (1 Cor. 15:3-8), was seen to eat fish (Luke 24:41-43), invited physical touch (John 20:27), plus talked with the witnesses (Matthew 28:9-10, 16-20), all over a period of several weeks (Acts 1:3). The witnesses were so convinced by the proofs of the physical reality of what their senses perceived—proofs that Jesus was physically alive after His death—that they testified to the resurrected Jesus in spite of persecution and suffering.

If radical sensory skepticism were true, then the witnesses' suffering for the truth of what they heard, saw, and touched—so we could reasonably believe their reports—would be in vain. Happily, radical sensory skepticism is not true.

Next: Kantian skepticism.

P.S. The above column is a slightly revised excerpt from my larger article, "Reasonable Skepticism about Radical Skepticism," Christian Research Journal, Volume 31, Number 5 (2008): 30-38.

Apologia columns on radical skepticism:

• Radical Skepticism (Part 1 of 1): Funky/Pop Skepticism
• Radical Skepticism (Part 2 of 4): Sensory Skepticism
• Radical Skepticism (Part 3 of 4): Kantian Skepticism
• Radical Skepticism (Part 4 of 4): Linguistic Skepticism
• Skepticism Concerning Colours?
• Nietzsche's Skepticism

(Hendrik van der Breggen, PhD, is assistant professor of philosophy at Providence College, located in Otterburne, Manitoba, Canada. The views in this column do not always reflect the views of Providence.)

Radical Skepticism (Part 1 of 4)

APOLOGIA
By Hendrik van der Breggen
The Carillon, September 2, 2010

Radical Skepticism, Part 1 of 4: Funky/Pop Skepticism

Radical skepticism concerning the external world is the philosophical view that we cannot have accurate knowledge about the physical reality that exists outside our minds. If radical skepticism were true, then we could not know the external world. (Moreover, we could not know the external world's revelation of God, whether God's revelation is via the heavens declaring His glory or via Scripture's pages presenting truth about Jesus Christ.)

Should we be persuaded by radical skepticism? I think not.

There are at least four types of radical skepticism. Today we will look at funky/pop skepticism (my label). Funky/pop skepticism is probably best explained by considering some examples. (The examples are a bit weird, hence funky. Also, contemporary popular culture promotes the notion, hence pop.)

Consider the movie The Matrix. In this story what we perceive to be real is merely a computer-generated illusion, but in actuality, each of us is floating in an amniotic-sac-like pod with our nervous systems and brains wired into a common virtual reality. Whatever we sense—that is, whatever we think we sense—is merely what a supercomputer programs for us to sense. Nothing we see, hear, smell, taste, or touch is real.

Prior to The Matrix, philosophers entertained the possibility that we are merely brains in vats, kept alive by a mad scientist who feeds us patterns of electrical impulses which mimic our sensory organs.

Consider also the possibility that you are at this very moment dreaming. This example originates with René Descartes (1596–1650) and has been recently revived in the movie Inception. Whatever you see, hear, smell, taste, touch—and read—is simply part of your dream.

How do you know that, right now, you are not in something like The Matrix? Or that you are not a brain in a vat? Or that you are not dreaming?

I might answer that I believe I am not in The Matrix because I haven’t yet met agent Smith. (Smith, according to The Matrix, is a representative of the supercomputer.) The skeptic responds that the supercomputer wants to keep me in the dark.

Or I might argue that I am not a brain in a vat because I can feel my skull with my hands. The skeptic answers that the mad scientist has wired me to perceive that I am touching my skull when in fact I’m not really touching anything.

Or let’s say that I argue that I’m pretty sure that I’m not dreaming because I heard my alarm go off this morning. The skeptic answers that it’s not at all unusual for one to hear one’s alarm go off in one’s dream.

Alarmingly (sorry), any evidence that I present against the skeptic can be subsumed under the Matrix hypothesis, or brain-in-a-vat hypothesis, or dream hypothesis.

Should I give up my knowledge of the external world?

Answer: No.

There is a reasonable way to answer the funky/pop skeptic. In fact, there are five ways, which together constitute a formidable cumulative case argument.

First, we can point out, following the philosopher Ludwig Wittgenstein (1889–1951), that to imagine a doubt is not really to doubt. I can imagine that I am in a computer-generated world, but that doesn’t mean I really believe it. Simply put: imagining isn’t doubting. To think otherwise is to confuse two distinct cognitive categories.

Second, we can point out that if one were to be convinced of any of the above skeptical hypotheses, then one would be confusing logical possibility with plausibility/probability. Yes, it’s logically possible that the moon is made of green cheese (i.e., there is no logical contradiction in this claim), but from this it doesn’t follow logically that the moon is actually made of green cheese. In other words, the mere logical possibility of X is not the same as an adequate justification for X; therefore, the mere possibility of doubt does not constitute sufficient grounds for doubt.

Third, we can point out that there is no compelling reason to accept any of the funky/pop hypotheses: after all, all we have is the skeptic's mere assertion (of a mere logical possibility).

Fourth, we can point out that belief in any of the funky/pop hypotheses requires a denial of many of our prior beliefs that are logically incompatible with those hypotheses. Furthermore, these prior beliefs are not without epistemic weight—they also count as contenders for knowledge.

Fifth, we can point out that if, for the sake of argument, we accept mere assertions of bare logical possibilities as sufficient grounds for the truth of those assertions, then, to be consistent, we should believe all mere assertions of logical possibilities as truths. This, however, would mean that all logical possibilities are true, which is plainly absurd.

We would have to believe that The Matrix is true, and that the brain-in-a-vat hypothesis is true, and that the dream hypothesis is true, and that The Lord of the Rings is true, and that Batman is true, and that the moon is made of cheese, and that the moon isn’t made of cheese, and…you get the picture.

In other words, rational persons can weigh the pros and cons—in this case, one pro constituted by a mere assertion of funky/pop skepticism versus five cons or counter-considerations—to conclude that it is reasonable not to believe funky/pop skepticism.

We will examine some other forms of radical skepticism next time.

P.S. The above column is a slightly revised excerpt from my larger article, "Reasonable Skepticism about Radical Skepticism," Christian Research Journal, Volume 31, Number 5 (2008): 30-38.

Apologia columns on radical skepticism:

• Radical Skepticism (Part 1 of 1): Funky/Pop Skepticism
• Radical Skepticism (Part 2 of 4): Sensory Skepticism
• Radical Skepticism (Part 3 of 4): Kantian Skepticism
• Radical Skepticism (Part 4 of 4): Linguistic Skepticism
• Skepticism Concerning Colours?
• Nietzsche's Skepticism

(Hendrik van der Breggen, Ph.D., is assistant professor of philosophy at Providence College, Otterburne, Manitoba, Canada. The views in this column do not always reflect the views of Providence.)