« Podcast on Descartes' Meditations | Main | Philosophy Bites - Podcasts with Top Philosophers Launched »

May 30, 2007



I sometimes wonder if Zeno's Arrow Paradox has really been solved. Or even if it has, after some fashion, whether it is raising an interesting metaphysical point. If you look at the world at a specific instant in time, what is it about a moving arrow that distinguishes it from one at rest?

Tim Lacy

Thanks! I never realized the depths of the subject before reading this post. - TL


I think you need to amend the explanation of the sorites paradox a bit; I had to look it up on Wikipedia to be sure what you meant. (2) needs to say something like "Take a single grain away from a heap and it will not cease to be a heap. And another. And so on. Until you have only one grain left".

Michael Clark

To Heraklites

See the entry on The Arrow in my book.

Michael Clark

To potentilla

Thanks. A good idea. I'll get it changed to your suggestion.

nigel warburton


jim rogers, gosford, australia

The paradox of The Body, and the paradox of The Ship of Theseus (Plutarch, Hobbes):
Over a period of years, in the course of maintenance a ship (Ship A) has its planks replaced one by one. However, the old planks are retained and themselves reconstituted into a ship (Ship B). At the end of this process there are 2 ships. Which one is the original ship of Theseus?

The human body comprises up to 100 trillion total cells (reports vary). Only a proportion of them are human cells. The rest are parasites and assorted microbes, much smaller than our human cells. Over 1000 different species of bacteria live in the human body. Each of your cells contains about 10 billion protein molecules of approximately 10,000 different varieties. There may be 200,000 different proteins. The average cell makes 2,000 proteins/sec, and 173 million /day, ==> if 74 trillion cells in the body, = 1.28x10²¹/body/day. Each cell is continually involved in billions of chemical reactions.

100,000 or so cells are dying off every second and replaced. In a human body a trillion atoms may be replaced every millionth of a second. Every atom in the body get turned over at least once if not many times every few years. They are now in plants, other animals including humans, or the soil, air and oceans.

A person (A) may have no atoms in common with his former body (B) from a previous period of his life, and the tiny number of possible atoms which may again be present will be in a different cell and location. The existence of a soul involves a hypothesis without proof. If a person doesn't have one, then all that A and B have in common is part of their history and memories, plus a genetic code, changing and older cellular structural blueprints including some common neuronal structures/pathways, and personality traits. The bundle that comprises self A now is different to his former B self. So is he the same person, or different?

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Comments are moderated, and will not appear until the author has approved them.

Your Information

(Name is required. Email address will not be displayed with the comment.)

My Photo

Get Virtual Philosopher by email...

Enter your email address:

Delivered by FeedBurner

My Podcasts

My Art and Photography Weblog

Philosophy: The Classics

Philosophy Bites

Ethics Bites