I just received the book I ordered from Amazon called Externalism and Self-Knowledge. The book is more or less a collection of relevant articles from different philosophers who were writing about the same topic or at least relevant to the topic. The topic is relatively new to me, so I might miss out a couple nuances, subtleties, or points. Nonetheless, I do know enough of the basics to write about them in my blog. Basically, the topic of Externalism and Self-Knowledge is a debate about whether or not Externalism is compatible with Self-Knowledge.
In the context of Philosophy of Mind, Externalism is the thesis about a meaning of mental contents. Specifically, Externalism is committed to an idea that a meaning of mental contents is at least partly determined by its environment, rather than the internal features of the mind. So, the content of my thought “The cat is on the mat” is determined by an environment that the cat is sitting on the mat. Notice, however, that Externalism is not merely stating that any content of our thoughts is caused by an environment. This is a prima facie trivial truth that even an Internalist accepts (An internalist believes that mental contents are individuated or determined by internal states). An Externalist, however, is stating that the meaning of the mental content is also constituted by its (causal) relation to an environment. So, we can individuate a meaning of mental contents based on its relation to an environment.
There is the famous thought experiment called the “Twin-earth” by Hillary Putnam. Suppose that there are the original earth and an identical planet called “twin earth”. Furthermore, twin earth also has people who are identical to us in every way (ignore the obvious question about how these people coincidentally happen to have the exact same evolutionary history as our own). There is, however, one difference: twin-earth doesn’t have H2O, but rather something that looks like water constituted by XYZ. Apparently, XYZ is called “water” in twin earth. Both Oscar and twin-Oscar have thoughts about water, but Oscar has thoughts about H2O, whereas twin-Oscar has thought about XYZ. Even though both share the same neurophysiology in an extremely similar environment, both of them have different thoughts about water. Putnam concludes that “meaning ain’t in the head”.
This thought experiment inspired many philosophers to believe in Externalism, but this leads them to a prima facie conundrum. A lot of these philosophers also believe in a semi-traditional view of Self-Knowledge inspired by Descartes. They believe that self-knowledge possesses a kind of private epistemic privilege that grants an immediate a priori knowledge of one’s mental content. However, knowing facts about one’s environment requires an a posteriori knowledge of contingent facts. On one hand, It appears that if we have an a priori knowledge of our own mental contents that are constituted by their (causal) relation to an external world, then we have an a priori knowledge of an external world. On the other hand, it could be that knowing my own thoughts is not a priori, but rather a posteriori, since their meaning is determined by an environment. So, knowing our own thoughts might just be as a posteriori as experiencing any given environment. We have an apparent dilemma: either we have an a priori knowledge of an entire world or we do not have an a priori knowledge of our own conscious thoughts. The first horn sounds implausible, since it is already clear that we do not have an a piori knowledge about the world. The second horn is disturbing for externalists who are committed to a semi-Cartesian view of self-knowledge, since they do believe that we at least have some a priori knowledge about our own thoughts.
There is one well known thought experiment in this debate called the Switch case. The purpose of this thought experiment is to argue for the second horn of the dilemma. Suppose that unbeknownst to Oscar, he was teleported to twin earth by technologically advanced martians. Oscar is oblivious that the teleportation took place, since the place he was teleported to looks exactly like his home planet. When Oscar comes across a water-like XYZ, the content of his thought is indistinguishable from that of H2O. In fact, Oscar mistakenly thinks that the content of his thought is “H2O”. If one accepts that Oscar’s mental content is determined by his environment, then his mental content in twin-earth should be XYZ. However, Oscar mistakenly thinks that his content is not XYZ, but rather H2O. If Oscar’s self-knowledge about his content is mistaken, then it doesn’t seem like he has an a priori knowledge about his content.
It is important, however, to emphasize that the thought-experiment would clearly work if an a priori knowledge or warrant is suppose to be infallible. However, many philosophers who are committed to the existence of a priori knowledge allow that it can be defeated by evidence. So, it is not clear if the thought-experiment shows that self-knowledge is not a priori. However, one could argue that we often see self-knowledge as an area of knowledge that seems most secured than any form of knowledge. The thought experiment seems to tarnish this picture of self-knowledge beyond redemption. Nonetheless, someone else could insist that in practice the traditional view of Self-Knowledge is still valid, since the switch case never really happens. Peter Ludlow argues that the switch case does happen when we travel to different linguistic communities that use some of the same words, but with different meaning or reference.
I personally think this is an interesting topic so far, so I’m going to read the book with an anticipation of developing more interest.