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Single Idea 22747

[filed under theme 27. Natural Reality / A. Classical Physics / 1. Mechanics / a. Explaining movement ]

Full Idea

If a ship moves forward and a man carries a rod backwards on it, then it is possible for an object to move without quitting its place.

Gist of Idea

A man walking backwards on a forwards-moving ship is moving in a fixed place

Source

Sextus Empiricus (Against the Physicists (two books) [c.180], II.056)

Book Ref

Sextus Empiricus: 'Against the Physicists/Against the Ethicists', ed/tr. Bury,R.G. [Harvard Loeb 1997], p.239

A Reaction

[summary of a verbose paragraph] The point is that you cannot define movement as change of place (contrary to Russell's proposal!). The concept of a place seems to be relative. Walking on a treadmill.

Related Idea

Idea 14168 Occupying a place and change are prior to motion, so motion is just occupying places at continuous times [Russell]

The 32 ideas with the same theme [explaining why not all things are stationary]:

1713 Thales must have thought soul causes movement, since he thought magnets have soul [Thales, by Aristotle]
12269 All things are in a state of motion [Heraclitus, by Aristotle]
5115 It is feeble-minded to look for explanations of everything being at rest [Aristotle on Parmenides]
455 That which moves, moves neither in the place in which it is, nor in that in which it is not [Zeno of Elea]
3059 There is no real motion, only the appearance of it [Melissus, by Diog. Laertius]
24044 Movement can be intrinsic (like a ship) or relative (like its sailors) [Aristotle]
24045 Movement is spatial, alteration, withering or growth [Aristotle]
1738 Practical reason is based on desire, so desire must be the ultimate producer of movement [Aristotle]
1739 If all movement is either pushing or pulling, there must be a still point in between where it all starts [Aristotle]
399 If the more you raise some earth the faster it moves, why does the whole earth not move? [Aristotle]
20063 Motion fulfils potentiality [Aristotle]
5114 If movement can arise within an animal, why can't it also arise in the universe? [Aristotle]
5116 When there is unnatural movement (e.g. fire going downwards) the cause is obvious [Aristotle]
3063 Motion can't move where it is, and can't move where it isn't, so it can't exist [Pyrrho, by Diog. Laertius]
5696 If there were no space there could be no movement, or even creation [Lucretius]
5706 Atoms move themselves [Lucretius]
22747 A man walking backwards on a forwards-moving ship is moving in a fixed place [Sext.Empiricus]
1899 Does the original self-mover push itself from behind, or pull itself from in front? [Sext.Empiricus]
1900 If time and place are infinitely divided, it becomes impossible for movement ever to begin [Sext.Empiricus]
1901 If all atoms, times and places are the same, everything should move with equal velocity [Sext.Empiricus]
17234 Motion is losing one place and acquiring another [Hobbes]
15866 Newton reclassified vertical motion as violent, and unconstrained horizontal motion as natural [Newton, by Harré]
12484 Motion is just change of distance between two things [Locke]
12985 Maybe motion is definable as 'change of place' [Leibniz]
19348 All that is real in motion is the force or power which produces change [Leibniz]
12696 Bodies are recreated in motion, and don't exist in intervening instants [Leibniz]
4786 Russell's 'at-at' theory says motion is to be at the intervening points at the intervening instants [Russell, by Psillos]
14168 Occupying a place and change are prior to motion, so motion is just occupying places at continuous times [Russell]
15243 We perceive motion, and not just successive occupations of different positions [Harré/Madden]
20365 We only see points in motion, and thereby infer movement [Rescher]
4224 If motion is change of distance between objects, it involves no intrinsic change in the objects [Lowe]
14725 Maybe motion is a dynamical quantity intrinsic to a thing at a particular time [Sider]