A Nice Point..

..from here. The author neatly skewers an argument for equating knowledge with having justificational certainty…

Proponents of.. [the argument from linguistics] ..claim that it is absurd to say, “I know proposition p is true, but there is a possibility that proposition p is false.” It seems as though this is an oxymoron. For them to state that they know that proposition p is true excludes that they would concede that proposition p may be false, and likewise, the concession that proposition p may not be true excludes the subject from saying he or she knows that proposition p is true.

Answering the Skeptic: Part Four

Skepticism and Rationality

Part three of this series dealt with the objection that knowledge of the external world is impossible, depending on a Reliabilist account of knowledge to rob the skeptic’s conjecture of its deletorious consequences. Yet I doubt the skeptic is fully satisfied. There remains another concern, that even if we have knowledge of the external world, we could never be in a position to rightfully claim that knowledge. Though we base our knowledge claims off of a conception of the world upon which our beliefs would be true and reliably formed, we are not entitled to that conception in the first place: a stubborn irrationality is at the heart of our knowledge claims. So let’s look at rationality.

Answering the Skeptic: Part Three

All the World to Gain

At the end of the last post we arrived at a conception of knowledge called Reliabilism. According to this conception, the necessary and sufficient conditions for knowledge are (i) that the knower have a belief, (ii) that the belief is true, and (iii), that the belief is produced by means that are reliable in the circumstances. Recall the skeptical challenge:

Imagine, for a moment, that the world is not as it seems to be. Imagine that the experiences which are so formative in your conception of the world are not the product of various objects they superficially indicate, but are instead the product of a carefully designed computer programme. You are a brain in a vat, and your experiences are stimulated by electrical impulses, sent from a supercomputer via electrodes attached to various parts of your brain. If that were the case, how could you know it? But perhaps it is the case. How, then, can one claim to know anything about the external world?

We can now reply.

Answering the Skeptic: Part Two

What is Knowledge?

Let’s begin with the obvious. Suppose that the brain-in-a-vat hypothesis given in the previous post were true. In that case, a great many of our beliefs about the external world would be false, and this, without needing skeptical argument, would be sufficient for our lack of knowledge on these matters. So falsehood is a disqualifying condition for knowledge, and what is just the same thing, truth is a necessary condition. But, what is almost as obvious, truth is not sufficient for knowledge either. There are as many truths as there are falsehoods, perhaps even an infinite number of each, whereas the knowledge of such beings as yourself and I are partial and finite. Moreover, it is beings like you and I to whom that knowledge belongs, and thus is essential to knowledge that it be possessed by a knower. So we need some further condition which constrains knowledge in these respects, and it is customary to take this extra condition to be belief.

Still, our definition is not nearly sharp enough. For consider that our skeptical hypothesis (“a possible state of affairs that is both consistent with the evidence we have, and is inconsistent with our usual hypothesis based on that evidence”) manages to cast knowledge into doubt even if we insist that our beliefs about the external world are true. Such hypotheses may be laughable, yet it seems their mere possibility is enough to challenge our knowledge claims. And so we need to add to our definition a third condition, one which, even if it does not confute the skeptic, shows why skeptical arguments are effective.  

Answering the Skeptic: Part One

The Skeptical Challenge

My concern, in this and posts to follow, is to give an answer to the skeptical challenge, one that does justice to the force of skeptical arguments but allows for both knowledge and rational belief concerning the external world.

Imagine, for a moment, that the world is not as it seems to be. Imagine that the experiences which are so formative in your conception of the world are not the product of various objects they superficially indicate, but are instead the product of a carefully designed computer programme. You are a brain in a vat, and your experiences are stimulated by electrical impulses, sent from a supercomputer via electrodes attached to various parts of your brain. If that were the case, how could you know it? But perhaps it is the case. How, then, can one claim to know anything about the external world?

The above sketches a familiar skeptical line of thought. The skeptic begins with a distinction between appearance and reality, noting that what appears to be may differ from what is. He then proceeds to offer a skeptical hypothesis – that is, he describes a possible state of affairs that is both consistent with the evidence we have, and is inconsistent with our usual hypothesis based on that evidence. In the above case, the brain-in-a-vat hypothesis counts as a skeptical hypothesis because our experiences might have been the same were we brains-in-vats, but obviously the hypothesis that we are brains-in-vats contradicts our usual picture of how we relate to the world as embodied beings. This is implied to undermine our claims to know otherwise.