Many years ago someone asked a question I'm still unable to answer. I think it falls under 'perception'. I traveled quit a bit and had many interesting experiences as a woman working for a multi-national corporation. While in Pakistan, I met a co-worker's wife. We got along very well and had a great time discussing something we both enjoyed very much - cooking. She turned to me and asked, "What does an avocado taste like?" They just weren't available to her in Lahore. She had seen pictures and read recipes but never had one. I couldn't relate the taste through comparison because avocadoes are unique. I could talk about colour or texture but that didn't satisfy her question about flavour. I asked many people when I got home. The answers all related to texture or colour. I had an interesting disagreement over the answer, "It tastes green." How do you express or talk about flavour without a base to compare against? How can someone share perception without a common experience? Thanks Nadine

That's a great example, and a great question. There are a number of obstacles to conveying the taste of an avocado to another person in words. Some are practical and some are philosophical. First, even those of us who've tasted avocados will have difficulties recalling the taste when we're not actually tasting it. I bet I could do pretty well distinguishing avacados from other substances in a blind taste-test, but my current acquaintance with the taste is not so determinate right now as I sit in my office trying to conjure it up while drinking water. I would have an easier time describing the taste to your friend if I were currently eating an avocado. Second, we seem to have no "purely qualitative" language for picking out the way things taste to us "from the inside". By this I mean that all the descriptions we might use seem to make inelimanable reference to some external substance, and then draw comparisons with the taste it typically causes. Even "salty" means something like "tastes similar to...

If every distinct mental state has a distinct ("corresponding") physical state, how could we tell which was causing which at any given moment? I'm sure that in certain contexts it would be more practical to answer that the mental state was caused by the physical state (e.g., "P is just irritable because he hasn't eaten"), and that in certain other contexts it would be more practical to answer that the mental state caused the physical (e.g., "P moved his hand because he decided to")--but is there any context-free answer to this question, i.e., the question as to whether the mind controls the body or whether the body controls the mind at any given moment?

Any answer to the mind-body problem struggles to account plausibly for the causal relations that seem obviously to run in both directions between mind and body. For the dualist, who holds that mental states and physical states are distinct, your question is accute: how could a mental state really cause a physical state if physical states bring about one another comprehensively (or even deterministically). The effects of a given mental state seem pre-empted by the physical state that corresponds with it. Some dualists--"epiphenomenalists"--embrace this problem and hold that mental states, though caused, are themselves causally ineffective. But many have found this problematic: for one thing it's unclear how we could know about mental states (or any entities) that have no causal effects; more damaging, though, is just the sense that this does a deep injustice to the way our mental states present themseleves to us from the inside. You seem to experience mental causation consciously when you decide to...

I read an article in Scientific American magazine discussing the existence of parts of the brain that regulate awareness of the self. Part of the article examined the damage or destruction of these neurological pathways through diseases like Alzheimer's. If it can be scientifically shown that the self ceases to exist in some Alzheimer's patients, what is left that walks, talks, thinks, and remembers? Is it a new self or a non-self or something totally different?

This is a good but difficult question. The answer, I think, depends upon what you mean by a "self". (Many people, including those who believe in immaterial, unified, and potentially disembodied "souls" would not agree that the notion of a "self" is open to several different, but equally useful characterizations.) If we require for the existence of a "self" the type of cognitive integration and global powers of rational understanding and planning that sadly break down in such patients, then, when the break down has gone too far, there remains no self in this sense. Nevertheless, there remains, of course, a body with all sorts of sophisticated abilities (to walk, to speak, etc.); and for all that I've said, there may remain a soul.

What do philosophers mean by the term 'mental content'? My initial reaction to the phrase was to take it to mean something like 'the meaning of a thought, belief, etc.' But this interpretation seems...unexplanatory. It seems to me that things don't just MEAN; rather they mean TO some individual/group. (X doesn't just mean Y; X means Y to Z.) For any given thought/belief/whatever (X), we could imagine infinite different Zs, and through these Zs, infinite different Ys. Which Zs are the relevant ones? Why is whatever distinction is drawn between relevant and irrelevant Zs drawn as it is? Or is my vague conception of mental content as the meaning of a thought, belief, etc. not in line with how philosophers use the term? If so...what do they mean by it?

Although "mental content" is a term of art, and used in different ways by different philosophers, most take it to be the way--the proposition or information--that a mental state represents the world as being. My belief that Bush is president and my belief that Alaska is large differ in mental content--the first represents the world as containing a guy named "Bush" who is president, the second a large state called "Alaska". By contrast, my belief that it's sunny outside and my desire that it be sunny outside share the same mental content, though they constitute different attitudes towards this content. Even if this notion of mental content is clear enough, there are a number of important and unsettled issues surrounding it. One prominent issue is whether (and if so exactly how) the contents of our mental states are determined by features beyond the surface of our skin--most notably our environment and socio-linguistic setting. See for more on this....

In an illegal drug such as LSD, the chemical reaction with your brain causes you to see things, such as motion trails or lighting effects, that cannot be seen by someone who is not on the drug. Assuming that is true, would it be possible that LSD gives its user the ability to see something that actually exists but cannot be seen by the human eye without the chemical adjustment of the drug in the brain?

I suppose it depends upon how you understand these effects. Take "motion trails". If we regard these as illusions--that is, we hold that there aren't really colored trails that follow a moving object like colored silk scarves attached to the end of the object--then the drug may be allowing us to have certain illusory experiences that we might not otherwise achieve, but it isn't allowing us to see colored trails that actually follow objects, since there are none. So LSD allows us to have an experience as of a motion trail, but not to actually see one in the world. (This is just what we should say about the straight pencil that looks crooked in a glass of water: I have a visual experience as of a crooked pencil, but am not actually seeing one, since there is none to be seen.) This is not to deny, though, that drugs may heighten our veridical perception of our environment. That to me is the most interesting feature of drugs. Perhaps LSD does this at times, but I wouldn't know.