Hilary
Putnam’s Twin Earth thought experiment has inspired and troubled
epistemologists and philosophers of mind for almost thirty years.  Here it is:
Imagine a person, call her ‘Sally’, who is familiar with water without knowing
its chemical constitution.  Sally drinks water, swims in it, thinks about it
and refers to water by the term ‘water’.  Now imagine that Sally, instead of having
been brought up on our actual planet Earth, had instead grown up on Twin Earth,
so that Twin Earth is exactly like Earth, except that the stuff that feels,
tastes and looks like water has the chemical constitution XYZ on Twin Earth €“
as opposed to H₂O on Earth.  What puzzles philosophers is that Sally
seems to have different thoughts when she thinks about water, depending on
whether she is on Earth or on Twin Earth, while it is stipulated that
everything about her, including her brain states, are identical.  The content
of Sally’s thoughts is partly determined by her surroundings.

Should
anyone be troubled by such a result?  Jessica Brown, reader for philosophy at
the University of Bristol, argues in an exceptionally clearly written book that
at least epistemologists need not worry.  Yes, the content of thoughts and
propositional attitudes such as beliefs, desires, fears and hopes is partly
individuated by the subject’s environment.  Sally does have different thoughts
depending on whether she is on Earth or Twin Earth, even if she has got no idea
where she is, and even if she is the same Sally down to the very last molecule
and neuronal state.  But no, the epistemological consequences of this construal
of mental content are not as threatening as they are often made out to be. 
Anti-individualism, as Brown calls the view formerly sometimes known as
‘externalism’, is compatible with a range of assumptions that philosophers hold
dearly.

After
a brief introduction that sets up the task and provides some helpful
distinctions, Brown’s Anti-Individualism and Knowledge establishes this
compatibility by offering a series of largely self-contained arguments. 
Firstly and most importantly it examines the claim that anti-individualism is
incompatible with the idea that subjects have privileged access to the contents
of their own propositional attitudes.  Does anti-individualism entail that I
have to investigate my environment in order to know what I think?  Secondly,
does anti-individualism undermine our notion of a rational subject because the
anti-individualist individuation of reasons (and of what they are reasons for)
makes it possible that even the most reliable and self-aware logician overlooks
good inferences and draws bad ones?  And thirdly, does anti-individualism have
the absurd consequence that a subject who knows that her thoughts are
individuated by her environment can make inferences from her thoughts to her
environment, thereby finding out things about her surroundings only by engaging
in introspection and some clever philosophy?

Brown
concludes that anti-individualism does not have these problematic epistemic
consequences.  It does not threaten our privileged access to our own thoughts,
because the situations in which we would fail to notice that our thoughts have
changed can be disqualified from counting as relevant alternatives, just as
some skeptic challenges can be shown as failing to undermine knowledge because
they do not provide relevant alternatives to the actual knowledge acquisition. 
Even anti-individualists who concede that they sometimes unknowingly hold
contradictory beliefs can conceive of themselves as rational, because they
cannot be blamed for their rare logical failings.  And nobody, no matter how
anti-individualist her views, can validly infer from her own thoughts to her
environment.

But
although these findings are presented as the conclusions of the book, some of
Brown’s most ambitious claims appear as side products of the process of arguing
for these conclusions.  Anti-individualism may not have the mentioned
"problematic consequences", but the attempt to accommodate it within
contemporary epistemology and philosophy of mind has important ramifications. 
Brown diagnoses that epistemologists have traditionally failed to acknowledge
the difference between reliable belief-forming processes and discriminatory
abilities.  In certain counterfactual conditions subjects may count as reliable
with respect to their own thoughts, while they lack some relevant
discriminatory abilities.  Brown also shows how the epistemological relevance
of some Twin scenarios can be contested, how Gareth Evans’ account of recognitional
singular thoughts should be modified, and what it means to be an
anti-individualist for those committed to explaining singular terms by appeal
to Fregean sense.

While
the explicit conclusions of the book directly affect the epistemology of
content, these collateral results may resonate more widely within contemporary
epistemology.  However it may well turn out that Brown’s organization of the
philosophical terrain will have the biggest impact on contemporary debates. 
The distinctions between different kinds of anti-individualism in both
descriptive and non-descriptive versions, the untangling of arguments and
sub-arguments, and the careful botanization of Twin thought experiments should
help tidying up the debate.  Keep this book handy if you tend to forget which
thought experiment fuels which argument against which species of
anti-individualism.

But
the impressively tidy conceptual organization of Anti-Individualism and
Knowledge comes at a price.  The author’s narrow focus and her
terminological discipline make the book unrewarding for non-philosophers. 
Brown’s arguments are stringent and her argument structures exemplarily
transparent, but sometimes, especially after yet another invitation to join
Sally on a trip to some Twin environment, it is not easy to see what is at
stake.  What is at stake depends, of course, on our take on propositional
attitudes ascriptions and epistemic states; on what we do when we understand
ourselves and others as entertaining a thought, having a belief, knowing
something, possessing a concept or making an assertion.  Brown ends the book
with one last neat distinction, categorizing these issues as matters of psychological
explanation and leaves the question of how they are affected by
anti-individualism "for another occasion".

But
perhaps they are not happily left for another occasion.  Depending on our
background views of propositional attitudes and concept possession we may hold
that a better understanding of psychological explanations is part of the point
of discussions of counterfactual content-individuation.  We may think that the
thought experiments are worth going through precisely because they help us understanding
what we do when we attribute concept possession, beliefs or knowledge to some
subject.  In what precise sense are propositional attitudes epistemic states,
how exactly does anti-individualism relate to justificatory externalism, how
can the role of propositional attitudes in psychological generalization and
prediction be squared with the kind of epistemic "blame" that Brown
invokes to save rationality?  It seems that a book that constantly draws from
intuitions pumped by thought experiments has to ensure that the reader is
always clear about the theoretical role of the concept under consideration. 
This is true of arguments as narrow contexts, which are thanks to Brown’s
clarity easy to keep track of, but also of the wider conceptual framework, which
here remains largely unquestioned.  Ultimately though the book has lots of the
virtues and not many of the flaws of any philosophical project that aims at
keeping things separately.  It certainly does provide impressive analytic work
and a wealth of complex arguments presented in great clarity.

© 2004 Dominique Kuenzle

Dominique Kuenzle is a PhD
candidate at the University of Sheffield.  He works on pragmatist accounts
of conceptual content and is interested in rational, discursive and epistemic normativity,
its ‘continental’ critics and rationalist defenses.

Categories: Philosophical