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27. Natural Reality / C. Space / 3. Points in Space

[minimal units that make up space]

13 ideas
Cantor proved that three dimensions have the same number of points as one dimension [Cantor, by Clegg]
     Full Idea: Cantor proved that one-dimensional space has exactly the same number of points as does two dimensions, or our familiar three-dimensional space.
     From: report of George Cantor (works [1880]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.14
Whitehead replaced points with extended regions [Whitehead, by Quine]
     Full Idea: Whitehead tried to avoid points, and make do with extended regions and sets of regions.
     From: report of Alfred North Whitehead (Process and Reality [1929]) by Willard Quine - Existence and Quantification p.93
Space is the extension of 'point', and aggregates of points seem necessary for geometry [Russell]
     Full Idea: I won't discuss whether points are unities or simple terms, but whether space is an aggregate of them. ..There is no geometry without points, nothing against them, and logical reasons in their favour. Space is the extension of the concept 'point'.
     From: Bertrand Russell (The Principles of Mathematics [1903], §423)
The concept of a 'point' makes no sense without the idea of absolute position [Quine]
     Full Idea: Unless we are prepared to believe that absolute position makes sense, the very idea of a point as an entity in its own right must be rejected as not merely mysterious but absurd.
     From: Willard Quine (Propositional Objects [1965], p.149)
     A reaction: The fact that without absolute position we can only think of 'points' as relative to a conceptual grid doesn't stop the grid from picking out actual locations in space, as shown by latitude and longitude.
The natural conception of points ducks the problem of naming or constructing each point [Kreisel]
     Full Idea: In analysis, the most natural conception of a point ignores the matter of naming the point, i.e. how the real number is represented or by what constructions the point is reached from given points.
     From: Georg Kreisel (Hilbert's Programme [1958], 13)
     A reaction: This problem has bothered me. There are formal ways of constructing real numbers, but they don't seem to result in a name for each one.
We should regard space as made up of many tiny pieces [Feynman, by Mares]
     Full Idea: Feynman claims that we should regard space as made up of many tiny pieces, which have positive length, width and depth.
     From: report of Richard P. Feynman (The Character of Physical Law [1965], p.166) by Edwin D. Mares - A Priori 06.7
     A reaction: The idea seems to be these are the minimum bits of space in which something can happen.
Why should the limit of measurement be points, not intervals? [Dummett]
     Full Idea: By what right do we assume that the limit of measurement is a point, and not an interval?
     From: Michael Dummett (Frege philosophy of mathematics [1991], 22 'Quantit')
Rationalists see points as fundamental, but empiricists prefer regions [Benardete,JA]
     Full Idea: Rationalists have been happier with an ontology of points, and empiricists with an ontology of regions.
     From: José A. Benardete (Metaphysics: the logical approach [1989], Ch.16)
We can identify unoccupied points in space, so they must exist [Le Poidevin]
     Full Idea: If the midpoint on a line between the chair and the window is five feet from the end of the bookcase. This can be true, but if no object occupies that midpoint, then unoccupied points exist
     From: Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Lessons')
     A reaction: We can also locate perfect circles (running through fairy rings, or the rings of Saturn), so they must also exist. But then we can also locate the Loch Ness monster. Hm.
If spatial points exist, then they must be stationary, by definition [Le Poidevin]
     Full Idea: If there are such things as points in space, independently of any other object, then these points are by definition stationary (since to be stationary is to stay in the same place, and a point is a place).
     From: Robin Le Poidevin (Travels in Four Dimensions [2003], 03 'Search')
     A reaction: So what happens if the whole universe moves ten metres to the left? Is the universe defined by the objects in it (which vary), or by the space that contains them? Why can't a location move, even if that is by definition undetectable?
Points are limits of parts of space, so parts of space cannot be aggregates of them [Lowe]
     Full Idea: Points are limits of parts of space, in which case parts of space cannot be aggregates of them.
     From: E.J. Lowe (The Possibility of Metaphysics [1998], 3.9)
     A reaction: To try to build space out of points (how many per cc?) is fairly obviously asking for trouble, but Lowe articulates nicely why it is a non-starter.
Surfaces, lines and points are not, strictly speaking, parts of space, but 'limits', which are abstract [Lowe]
     Full Idea: Surfaces, lines and points are not, strictly speaking, parts of space at all, but just 'limits' of certain kinds, and as such 'abstract' entities.
     From: E.J. Lowe (A Survey of Metaphysics [2002], p.254)
     A reaction: This is fairly crucial when dealing with Zeno's paradoxes. How many points in a line? How long to get through a point?
Maybe space has points, but processes always need regions with a size [Mares]
     Full Idea: One theory is that space is made up of dimensionless points, but physical processes cannot take place in regions of less than a certain size.
     From: Edwin D. Mares (A Priori [2011], 06.7)
     A reaction: Thinkers in sympathy with verificationism presumably won't like this, and may prefer Feynman's view.