# The Tortoise and the HareLoon

[draft]

Achilles glanced up from his writing atop the Tortoise[1] and exclaimed, “Look! The Hare has caught up.”

“No,” said the Tortoise apprehensively, “that isn’t the Hare, but the Hare’s all too clever cousin, the HareLoon.”

“A real HareLoon! I’ve only ever seen them in pictures.”

“Don’t get so worked up. She is always in a hurry but I can never tell if she is coming or going.”

“Ah, but you should know the HareLoon coming and the HareLoon going are one and the same,” said the HareLoon. She then faced Achilles, “I heard that Tortoise had you write many logical steps after starting with a mere three.”

With a wan smile Achilles murmured, “We’ve moved on from that now…”

“Yes” said the Tortoise firmly. “Have you heard of Moore’s Proof of the External World? It is just as short as the three lines of Euclid:

(A) Here is a Hand.
(B) Hands are external things.

(Z) The external world exists.

Achilles said, “We are now in agreement that Z follows logically from A and B. But…”

“But only if we accept A and B, does Z follow,” the Tortoise interjected. “However, I’m skeptical that hands are real at all.”

“Whatever do you mean?” asked the HareLoon, looking rather concerned for Achilles.

“Well, I might just be dreaming that there is a Hand in front of me. Or I could have eaten something disagreeable that is making me imagine things. Or someone is playing a trick on me.” The Tortoise continued, “I need a further statement to guarantee A:

(C) I am not being fooled into thinking a Hand is here.

Achilles cringed, palm to face.

“Fair enough, and I think I know where you are going with this,” said the HareLoon. “But before we worry about the External world, have you a proof of the Internal World?”

“What do you mean: Proof of the Internal World?” asked Achilles.

The HareLoon queried, “Let me ask you first: Would you know a HareLoon if you saw one? If so, please tell me how.”

In an official sounding voice the Tortoise recited: “The chief characteristic of a HareLoon is that it appears to be a Hare at some times, and appears to be a Loon at others.”

“Excellent,” replied the HareLoon. “Would you agree that the HareLoon does not itself change when it takes on these different guises? That is: the appearance of the Loon and the appearance of the Hare are in the thoughts of the beholder.”

“I suppose… The change is in the onlooker,” agreed the Tortoise.

“Then,” continued the HareLoon,

(A’) Here is a HareLoon.
(B’) HareLoons are internal things.

(Z’) The internal world exists.

“I distinctly remember Moore talking about hands and not HareLoons,” grumbled the Tortoise.

“Perhaps, but unlike hands you cannot be fooled into thinking HareLoons exist! We exist when, without change, we can appear to be a Hare or a Loon. Since we have agreed that this change is in your head, you can’t be mistaken about us switching in appearance between Hare or Loon. Hence when you think you see a HareLoon, you do see a HareLoon!

“Very Clever!” returned the Tortoise. “But what we want is the external — not internal — world. You’ve just argued yourself into my head and out of external existence. If you are only in my thoughts, it is a quick matter of logic to say that you aren’t anywhere eles.”

“Why Tortoise, that is the nicest thing you’ve ever said to me! To think, you’ve kept me in mind and maintained my existence, all these years. I should be flattered — or flattened, like you. I would take this paper thin existence (Cogito me papyrum esse, ergo sum)[2] but I don’t think I need to any longer.

“Answer me this: Who lives in this internal world? I’m here, and so are you! We have just agreed that I exist by you thinking, Cogito Ergo Es, and this is just the same as you existing by you thinking, Cogito Ergo Sum. So if I am a figment of your imagination, then so are you.”

“I am most certainly not a figment of my own imagination! You always were Loony, using Hairy reasoning.” said the indignant Tortoise.

“I don’t want to deny my existence any more than you yours, but if, as a quick matter of logic, you exclude others from existing, it loses its sense to say that you exist, either[3]. The only other thing that could have gone wrong is B’, that HareLoons are internal things. So we now have:

(A’) Here is a HareLoon.
(B’’) HareLoons are external things.

(Z) The external world exists.

Achilles shook his head, “You should have known, Tortoise… you can be in your house, but you’re still outside. If only your cousin were here, the Mock-Turtle would say: that while Achilles skill kills and the Tortoise disorders us (what tsuris!), the HareLoon’s Hume’s heir.”

[1] Carroll, Lewis. (1895) What the Tortoise Said to Achilles. Mind 4, No. 14: 278-280.
http://fair-use.org/mind/1895/04/what-the-tortoise-said-to-achilles

[2] Bouwsma, O. K. (1949). Descartes’ evil genius. Philosophical Review 58 (2):141-151.
http://home.sandiego.edu/~baber/analytic/Bouwsma1949.pdf

[3] Wittgenstein, Ludwig (1953/2003). Philosophical Investigations: The German Text, with a Revised English Translation. Malden, Ma, Blackwell Pub.
Relevant section §398 quoted below.