

On the Foundations of Geometry by Henri Poincaré (1898) - monort
https://archive.org/stream/jstor-27899007/27899007_djvu.txt

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Fede_V
For those that care about philosophy of science and mathematics, Poincare`
wrote a few excellent short books/long essays. In particular, he has some very
interesting books about the psychology of mathematical researchers and the
role of intuition.

[http://www-history.mcs.st-and.ac.uk/Extras/Poincare_Intuitio...](http://www-
history.mcs.st-and.ac.uk/Extras/Poincare_Intuition.html)

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amelius
> Our sensations cannot give us the notion of space. That notion is built up
> by the mind from elements which pre-exist in it, and external experience is
> simply the occasion for its exercising this power, or at most a means of
> determining the best mode of exercising it.

Can somebody explain what is meant here?

~~~
heurist
You need two eyes for depth perception. Neither individually can tell you
location, your mind figures that out by combining inputs. If you move your
arms and feel something near you, you still don't know where it is until your
mind relates it to other things your mind knows are near (or other parts of
your body). The sensation itself only provides information on existence, the
mind pieces together location. On the other side of experience, external
actions are entirely an effect of internal processes. Essentially, the mind is
a black box puppet master and the body is the puppet.

(I haven't read the passage, but that is my interpretation of your quote. I
always enjoy Poincaire's musings on the mind, they resonate strongly with my
own.)

~~~
Retric
_You need two eyes for depth perception._

This is false, you can get plenty of depth information from a picture or even
better a movie which is not stereoscopic.

~~~
ambicapter
Is that because the movie or picture are similar enough to the experiences we
previously had with our eyes?

~~~
Retric
People born with one good eye still generally develop depth perception. There
is a lot of research into this topic,
[https://en.wikipedia.org/wiki/Depth_perception#Monocular_cue...](https://en.wikipedia.org/wiki/Depth_perception#Monocular_cues)
has a good list of things that work just fine with one eye. But, it's not
obvious how much of these are learned vs instinctive.

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cbd1984
Why are you linking to an OCR of a scan? Link to the main page, where multiple
formats are on offer:

[https://archive.org/details/jstor-27899007](https://archive.org/details/jstor-27899007)

The main page even has a rather nice viewer to view the document in your
browser.

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shanusmagnus
Oftentimes stuff on the front page is posted as part of a recognizable cluster
of activity, but if that's the case with this submission I can't figure it
out. Can anyone help?

EDIT: Meaning, there's a theme; or one post comments on another post, or
provides background with which to interpret it.

