48 | New Scientist | 8 January 2022
The Jevons paradox is crucially important
today as we drive to reduce our carbon
emissions. As a technology becomes more
fuel efficient, it is tempting to use it more often.
But this can result in what is called a rebound
effect. All of us – especially those in power –
must understand this as we pursue net-zero
emissions targets. Simply increasing fuel
efficiency is at best an insufficient measure.
We also need zero-carbon technologies and
interventions such as taxes that prod human
behaviour in the right direction.
An even more prescient paradox today
is the paradox of tolerance, expressed most
famously by the philosopher Karl Popper
in 1945. It begins with the seemingly
unproblematic idea that being tolerant
means tolerating all views, but trouble
quickly follows:- To be completely tolerant, a society must
allow the expression of all views (0.9) - Intolerant views are views (1.0)
- To be completely tolerant, a society must
allow the expression of intolerant views (0.9) - The expression of intolerant views creates
intolerance, either in thought or action (0.9)
Conclusions: Therefore, to be completely tolerant,
a society must allow the creation of intolerance (0)
If we apply subjective probability, we see this
is a deep paradox. There is no straightforward
way of lowering the probability of any of the
claims, which suggests we might need to
modify our intuitions about tolerance at a
higher level. One way we can do this draws
from Tarski’s analysis of the liar paradox. We
might say that tolerance operates at two levels:
individual views and a meta-level notion of
tolerance that floats above those views and
says that both tolerant and intolerant views are
tolerated. However, what wouldn’t be tolerated
under the meta-notion is any intolerant view
that seeks to restrict the ground rule of
tolerance itself. A claim like “The xs are bad”
may be an intolerant view of any x, but
such a view can exist in this tolerant system
without paradox. However, “The xs should
not have the right to express their views”
cannot, because it violates the meta-level
rules of tolerant discourse.We see the fallout of this paradox all around
us in the way that social media companies
grapple with intolerant views – racism, sexism,
xenophobia and more – on their platforms.
Many social media sites, citing the need for
the free expression of ideas, have been hesitant
to ban those who espouse conspiracy theories,
misinformation and intolerance. A fuller
understanding of the paradox of tolerance
helps us see why this is reasonable but also
where the boundaries ought to lie. When the
views promoted restrict the abilities of others
to express their views, then this is a violation
of the ground rule of tolerance.
Identifying and rethinking paradoxes
can help us all understand the world around
us a little better. Engaging with them may
cause us to question our intuitions and
sometimes that can feel frightening. But
next time you encounter one it is worth
stopping to ponder for a while. When you
come away you might not be quite the same
person – whatever that means. ❚Margaret Cuonzo is a philosopher
at Long Island University Brooklyn
in New York and the author
of Paradox (MIT Press)Tr y i n g to b e
tolerant online
can tie us up
in paradoxes“ The Jevons
paradox is
important as
we drive to
reduce carbon
emissions”
GOLUBOVY
/GETTY^ IMAGES