“Why is the sky blue?” asks a curious child on the drive to school in the morning. The child’s parent, being a worldly person, happens to know the answer. “Blue is scattered more than other colors because it travels as shorter, smaller waves.” responds the parent. “Well why is blue scattered more?”

The blue color of the sky is caused by Rayleigh scattering of sunlight by the gases in the Earth’s atmosphere. Here you can see the degree to which  blue light is scattered more intensely than red light.

It’s a classic parenting scenario along with “Are we there yet?”, where a parent answers a question like, “Why is grass green?” and an incessantly curious child craves more with the word, “Why?” In moments of great patience, the child may get three, four, perhaps even five good answers, but when the reasons why approach facts about sub-atomic particles, it becomes increasingly difficult to answer. The practice of asserting facts and asking for reasons to believe those facts is an affair that epistemologists are interested in. Let’s assume it were possible to answer all of a child’s questions. What would the series of answers look like? What possibilities are there?

The Regress Problem is usually attributed to Sextus Empiricus, 160-210 AD. It was then called “the diallelus”, which is Greek for “through or by means of one another.”

This question is known as the “regress problem” in epistemology. If this conversation needed not end for practical reasons and the parent was all-knowing, would the conversation go on forever? The problem that this presents, and the reason it’s so hard to answer children’s unceasing questions, is that they seem to to go on forever . If this is the case, how can we ever raise the credibility, justification, or warrant of a claim? If reasons never reach some end, some inherent truth, how can justification ever reach our beliefs?

What possible solutions are there, and by corollary, how can we satisfyingly answer curious kids? Well, the logical space seems to only allow a few possible options:

1. The reasons end somewhere, that there is a foundational reason;
2. The reasons loop back on themselves, that reasons need only be coherent;
3. The reasons go on infinitely, that there is never a “last reason”;
4. We are just forming beliefs arbitrarily.

“If we keep going, we’re going to get something foundational.”

To visualize Foundationalism, think of an upside down pyramid.

Perhaps we build all of our justified beliefs on a bedrock of unquestionable foundations. This is plausible because there could be a set of reasons which it just does not make sense to question.

For instance, imagine again a conversation between a parent a child, say a father and his daughter. The father notices that that there is a blue smear on the living room wall, and on the basis of this forms the belief that his daughter was painting today. “You were painting today? Can I see your painting?”, he asks. The daughter, having not told her father she painted, wants to know his reason for thinking she painted. He responds, “I see the blue smear on the wall over there.” The daughter, in the mood to investigate the world, asks her father “What is the reason you believe that you see a blue smear on the wall over there?”

The intuition of Foundationalism, the theory which posits the end of the regress, is that questions like this, and questions about other foundational beliefs, are not valid questions. The father may be justified in responding, “What do you mean what is my reason for believing that I see a blue smear? I have no reason, I am appeared to as if there I see a blue smear.”

There are problems for this view, however. For instance, what foundation is there for mathematical knowledge? Is the father’s reasons for believing not that “When I am ‘being appeared to as if something is there’, then that something is in fact there?”

What are the conditions that makes something a legitimate foundational belief?

“If we keep going, my coherent reasons may repeat themselves.”

To picture Coherentism, try thinking about a spider’s web.

Imagine if in the process of describing to someone why the sky is blue, you at some point gave two separate reasons that both cannot be true. It would be perfectly natural for someone to question how you could hold both of them simultaneously, and you would likely try to resolve the conflict, to make your reasons cohere.

This is the intuition behind the Coherentist response to the regress problem, where the structure of justification is such that you will eventually loop back around on reasons. In the genealogy of your justification for any proposition, if the cycle is sufficiently large and doesn’t contradict other beliefs you have, hold say the Coherentists, then you have knowledge.

The problem that this view faces is that it is just is a longer form of circular reasoning. Where it seems to be acceptable to assert a proposition, and then when asked for a reason, supply that same proposition later down the line. Furthermore, there are plenty of perfectly coherent systems which are simply not true.

“This is just going to go on infinitely.”

The feeling that I get when I had a conversation with a child like this is that it just never stops. There is always another reason for believing something, it seems. For instance, if you say, “It’s twelve o’clock.”, and you’re asked “Why is it twelve o’clock?” Well, it is true that a reason that it is twelve-o’clock is that it is not 11:59, it’s also not 11:58, it’s also not…

There’s certainly an end to my knowledge, there’s probably an end to human capacity, but that doesn’t mean there’s an end to potential reasons for believing any given thing and that it goes on infinitely. This is the claim and intuition of Infinitism. The problem for this view is that if there’s always another reason to believe something, how can you “hook up” a proposition to the truth? Foundationalism has a bedrock and Coherentism has a network, but Infinitism still needs to come up with an account for raising the credibility of a proposition without foundations or coherent webs to be make it usable.

“Eventually, I’ll have no reason for believing what I do.”

The troubling aspect of the regress problem is that none of the answers are straightforwardly right, none of them are obvious. Yet if none of them are the right view, if the question of the structure of justification is a valid one, then we necessarily cannot be justified in any of our beliefs.

And this would be especially unsatisfying for inquisitive minds.

Paul Jones (Staff Writer, Rutgers University)
Paul is a senior studying philosophy and computer science at Rutgers University, New Brunswick. Transferring in the Spring of 2012, Paul earned an Associates in Liberal Arts from Mercer County Community College. An active member of the Rutgers undergraduate philosophy community, he holds leadership positions in the Philosophy Club, Undergraduate Journal, and Philosophy Honors Society. He has spent the last two summers working in research and development for Local Wisdom, Inc. of Princeton Junction, developing their WeatherWise and Photomash applications on Mac, iOS, and Android.

With thanks to Peter Klein, especially for his chapter in "Current Debates in Epistemology" with Carl Ginet.