
The regress argument against Cartesian skepticism (2012) [pdf] - lainon
http://individual.utoronto.ca/jmwilson/Wilson-The-Regress-Argument-Against-Cartesian-Skepticism.pdf
======
Amezarak
The paper argues that, because it is possible to doubt whether you are
doubting, and to doubt whether you are doubting you are doubting, and so on
and so forth, that this is an infinite regress, and because infinite regresses
are ugly and inconvenient, we should just throw out the whole chain and
declare ourselves sure of the world.

Frankly, this is a bad argument. The author mentions you can solve the regress
by simply denying that you can even know your own mental states, but dismisses
this on the grounds it doesn't help reach the desired conclusion. (!!!) The
author also goes to the trouble of claiming that some infinite regressions are
'psychologically stable' while others are not; no real argument is provided as
to why it matters whether a regress is such or not, except that the author
wants to get rid of inconvenient ones but not convenient ones.

The way to attack Cartesian skepticism is on its grounds and assumptions, not
to accept the premises. Descarte was right, if you assume his priors. There
are many people who do this, but the most systematic and determined one is
probably Heidegger. I suppose that people who want to believe in 'pure reason'
are not especially likely to go down that route, though.

~~~
jhinra
I'm with you. Replace "the external world exists" with some logical tautology
such as De Morgan's Law (not (A and B) <=> not A or not B). Formalism has all
sorts of gotchas, so I'm going to assert that it's possible to be skeptical of
De Morgan's Law being a tautology...

...which - as the author describes - implies I can go down that infinite
spiral of regressive speculation. But this is not the reason that De Morgan's
Law is a tautology.

Even worse, the author's argument really let's us assert anything, doesn't it?
I've read the paper twice and I can't see any protections from using this
argument to assert a contradiction.

------
comex
In short, could your mind be so utterly irrational that that you're mistaken
about the most basic questions of what you yourself know or think?

It's far from a purely hypothetical scenario. After all, while dreaming we
often follow nonsensical or self-contradictory chains of reasoning while
thinking they make perfect sense – hence the term "dream logic". There are
ways to try to identify that you're dreaming, and you can train yourself to
use them more consistently, but they're far from perfect. Sometimes it just
won't occur to you to do a dream test, and sometimes you'll fool yourself into
thinking you passed the test.

In my opinion, the only real solution is a pragmatic one. You can never be
certain that you currently have any degree of rationality, and so you can
never be truly certain about anything, period. However, you may as well
_assume_ you're rational for the purpose of making decisions. After all, if
you're currently 100% irrational, then you're going to make 100% nonsensical
decisions, and that's all there is to it. It doesn't really matter what you
believe or disbelieve, so it doesn't hurt to falsely believe that you're
rational. And there no point hedging on any action on the chance that you're
being irrational, because the idea that "if i'm irrational, it's best to
take/not take action X" is itself validated by rationality.

That said, there are degrees between complete rationality and complete
irrationality. In dreams you're often still partly rational, and you can also
get a sort of replica of rationality by training yourself to follow specific
thought patterns during times when you _are_ mostly rational (i.e. awakeness).
So it is theoretically possible to hedge based on the possibility that you're
dreaming – albeit not very useful, since making bad decisions in a dream
doesn't usually have any serious long-term effects. However, if you want to
narrow things down to more specific possibilities than "I'm dreaming" – as you
get to scenarios in which you're hypothetically being less and less rational,
it becomes less and less useful to hedge on those scenarios.

------
somethingroma
"Does the external world exist, as it so concretely seems?"

I know this is not the direction of the paper (or question) but physics
already gives us an astounding 'No!'.

~~~
Strilanc
Only if you subscribe to some pretty tortured interpretations of quantum
mechanics. QM still describes an objective state of the external world, and
exactly how it changes over time.

~~~
Quekid5
I don't think that's what the poster meant. I think it was probably more along
the lines of how you experience e.g. 'light' vs. what it actually _is_ :

    
    
       https://www.youtube.com/watch?v=FjHJ7FmV0M4
    

(The vast majority of light is effectively _invisible_ to you.)

------
yters
Cartesian skepticism always assumes some external entity manipulating your
mind. So, at least you can be sure you have a mind and there is an external
world.

------
bronzeage
I find it pretty easy to convince the world exist. If you assume you yourself
exist, and think, and if you assume the contrary, that the world out there
doesn't exist, you should ask yourself what alcohol and drugs are.

Because if the world out there doesn't exist, these things shouldn't effect
the way you think. If something is simulating the world for you, you have to
assume every time you drink, that thing alters the way you think somehow,
which means it can access your actual real brain, whatever it is.

Then that brain of yours, even if it's outside the world, must be so similar
to all the other brains you see, which are effected similarly by those same
substances.

~~~
naasking
> you should ask yourself what alcohol and drugs are.

A way of inducing an altered state of consciousness, just like sleeping and
meditating. This isn't problematic for the "brain in vat" scenario.

~~~
jstanley
If the brain is in a vat, why is it affected by alcohol outside the vat?

Sleeping and meditating are both internal to the brain, but alcohol only
becomes internal to the brain if it has some physical access to the brain.

For the brain in a vat theory to work, the computer controlling the simulation
would have to monitor the amount of alcohol that is in the bloodstream of the
simulated being, and adjust the alcohol in the vat accordingly?

~~~
somethingroma
I'm confused.

IF a consciousness was housed in a black box (a brain, but we're ignoring it's
internals) AND that black box had inputs connected to a computer that can send
signals to the black box that it WOULD interpret as signals of sight, sound,
touch, hunger, intoxication, etc.

THEN how is one suppose to conclude that they are not just a consciousness in
a box because they 'feel' drunk after they 'feel' they've ingested alcohol.

There's no need to monitor alcohol levels because the alcohol hasn't been
proven to exist!

~~~
chongli
I think your confusion arises from the fact that this discussion is about two
different thought experiments: the _brain in a vat_ [1] (a la _The Matrix_ )
and proper solipsism (which implies no real world at all, not even a vat). [2]

[1]
[https://en.wikipedia.org/wiki/Solipsism](https://en.wikipedia.org/wiki/Solipsism)

[2]
[https://en.wikipedia.org/wiki/Brain_in_a_vat](https://en.wikipedia.org/wiki/Brain_in_a_vat)

