MacBeth's Dagger and Other Illusions

Hylas objects to Philonous' idealism by claiming that on his view there is no way to distinguish between veridical appearances and illusions. In other words, idealism implies that the danger than Macbeth sees before his eyes but cannot clutch is just as real as the dagger he uses to kill Duncan. Is this a valid objection? How successful is Philonous' response?

Who Needs God?

Berkeley argues that, given the truth of idealism, God must exist. Is he correct? If so, how valuable is this argument? Does this argument give theists anything to cheer about? Or can we get something less than the omnipotent, omniscient and omnibenevolent God that Berkeley believes in?

Much Ado About a Mite

Berkeley argues for his idealism from the relativity of perception. He compares the size of a mite's foot as seen by the mite itself, by a human and by some smaller microorganism. What, exactly, is the argument? Is the argument successful? If not, how do we resist the sucking of all so-called primary qualities into the mind?

If a Trees Falls in the Woods. . .

If a tree falls in the woods and there is nobody around to hear it, does it make a sound?  Discuss.  You might want to define what you mean by a "sound," by "nobody," and perhaps even a "tree."

A Noble Failure?

Many of us in class found Descartes' foundational project to fail. Let's assume that he cannot justify all his claims to knowledge by an appeal to the Cogito. What can we learn from this failure? Should we look for a wider class of foundational beliefs? Should we avoid appeals to a God who is not a deceiver? Should we find a different way to justify beliefs that does not require an appeal to foundational beliefs?

A God Chasing Its Tail?

Antoine Arnauld (among others) famously accuses Descartes of arguing in a circle: the principle of clear and distinct ideas requires a non-deceiving God to validate it, but the proof of a non-deceiving God requires the principle of clear and distinct ideas. Is Arnauld correct? If not, why not? If not, at what cost?

The Cogito

In Meditation II, Descartes believes he has both defeated skepticism and discovered a foundational belief that he will use to justify all his other claims to knowledge. He argues that the very act of doubt proves that he exists. Is he right? Does the Cogito disprove skepticism? Even if it does is it a Pyrrhic victory -- or can this belief be the basis for the rest of his knowledge?

When the Walls Come Tumbling Down

Descartes realizes that some of the beliefs he thought were true turned out to be false. In the pursuit of knowledge he seeks to tear down his previous beliefs and build them up again upon a firm foundation. In other words, he is engaged in a foundational project, searching for a class of beliefs that themselves are not in need of justification in order to justify his other beliefs. But is this quest a misguided one? Do such beliefs exist? If not, does that mean that knowledge is impossible? Or is there some other way to justify our beliefs?