Online research in philosophy

Red-2 is a computer program for red-cell antibody identification, a piece of "normal science". Abstracting from Red-2, a general problem solving mechanism is described that is especially suited for performing a form of abductive inference or best explanation finding. A problem solver embodying this mechanism synthesizes composite hypotheses by combining hypothesis parts. This is a common task of intelligence, and a component of scientific reasoning. The work addresses the question, 'How is science possible?' by showing how a simple but powerful form of hypothesis synthesis is computationally feasible.

Suppose Ted is in an ordinary house in good viewing conditions and believes red, his table is red, entirely because he sees his table and its color; he also believes not-white, it is false that his table is white and illuminated by a red light, because not-white is entailed by red. The following three claims about this table case clash, but each seems plausible: 1. Ted’s epistemic position is strong enough for him to know red. 2. Ted cannot know not-white on the basis of red. 3. The epistemic closure principle, suitably restricted, is true. Stewart Cohen has called this three-way clash of intuitions the problem of easy knowledge. If we wish to resolve the clash without accepting skepticism, we seem to have two options. According to the hard argument, the best response is to reject 3. The easy argument rejects 2. But there may be a third alternative, the reverse argument, which rejects 1 without ceding a substantial amount of ground to the skeptic. In this essay I criticize recent versions of the reverse argument and the hard argument, thereby lending support to the easy argument.

Rabern and Rabern (2008) have noted the need to modify `the hardest logic puzzle ever’ as presented in Boolos 1996 in order to avoid trivialization. Their paper ends with a two-question solution to the original puzzle, which does not carry over to the amended puzzle. The purpose of this note is to offer a two-question solution to the latter puzzle, which is, after all, the one with a claim to being the hardest logic puzzle ever.

Suppose you are presented with three red objects. You are then asked to take a careful look at each possible pair of objects, and to decide whether or not their members look chromatically the same. You carry out the instructions thoroughly, and the following propositions sum up the results of your empirical investigation:

i. red object #1 looks the same in colour as red object #2.

ii. red object #2 looks the same in colour as red object #3.

Some ordinary language philosophers, including Stanley Cavell, have attacked certain tendencies of traditional philosophers as follows. E.g., when we say that something looks red to us, we imply that we think it isn't really red. Thus we arc breaking a rule of language when we say that something looks red to us when we know it is red. And thus there is something logically wrong with the traditional attempt, to say that what justifies us in thinking that something is red is its looking red to us. In this article it is maintained that the ?implication? invoked above is a contingent relation having to do with what makes a fact noteworthy, and that the existence of this implication does not show that there is anything logically wrong with the traditional positions being attacked.

We argue that relationalism entails an unacceptable claim about the content of visual experience: that ordinary ‘red’ objects look like they look like they look like they’re red, etc.

We present the simplest solution ever to 'the hardest logic puzzle ever'. We then modify the puzzle to make it even harder and give a simple solution to the modified puzzle. The final sections investigate exploding god-heads and a two-question solution to the original puzzle.

Suppose there is a red ball against a uniformly gray background moving toward my left. I am seeing the moving red ball. I am having a visual experience that carries the information (among other things) that [the ball] is red.1 Now supposing that I have the concepts RED and SEEING, and all my other cognitive (including introspective) mechanisms are intact and working normally, the job is to say exactly how I do come to know that I am seeing [the ball] as red. How do I come to know, as I shall sometimes put it, that I am seeing red?

How are we to define red? We seem to face a dilemma. For it seems that we must define red in terms of looks red. But looks red is semantically complex. We must therefore define looks red in terms of red. Can we avoid this dilemma? Christopher Peacocke thinks we can. He claims that we can define the concept of being red in terms of the concept of being red; the concept of a sensational property of visual experience. Peacocke agrees that his definition of red makes use of a concept that those who possess the concept of being red need not possess; namely, red. But he thinks that this does not matter. For, he says, the definition is justified provided we can specify what it is to possess the concept of being red in terms of the concept of being red. What he tries to show is that this might be so even if no-one could possess the concept of being red unless he possessed the concept of being red. Peacocke has two attempts at showing this. However, both these attempts fail. What Peacocke does show is something weaker. He shows that, using red, we can construct a concept that gives what he calls the constitutive role of the concept of being red; but, importantly, that it gives the constitutive role of red does not suffice for what Peacocke says is required for giving a definition. Thus, if we accept Peacocke's standard for definition, it follows that he gives us no way of avoiding the original dilemma. If this is right then perhaps we should join with those like Colin McGinn who think that we should give up our attempts to define our secondary quality concepts.

1.1 All mental terms are defined by private ostensive definition. 1.1.1 For example, the word "red" used to denote the conscious colour experience of red, as opposed to red light or red paint, is defined by attending to a red sensation and designating it "red".