Great question(s). I suggest that "the bottom line" philosophically in such matters involves whether your concept of a "laurel" enables you to identify the plant as distinct from other plants and things in general (including minerals, animals, computers,...). Another criterion that philosophers use involves identifying what features are necessary or sufficient for a thing to be what it is. Such an analysis will probably take shape in terms of differentiating a thing's essential characteristics from its accidental features. So, I assume that an essential feature of being laurel would be being a plant, but it would only be an accidental feature that the plant was used in ceremonies to make a kind of crown that was conferred on someone quite distinguished (a successful poet, say). Because things like laurels will have almost indefinitely many features (the way it tastes, the sound it makes or does not make, when harvested.....), we tend to prioritize what features are vital depending on the context. So, for...

The topic of knowledge is an old one, going back at least to Plato who wrestled with the difference between knowledge and correct opinion. The traditional, most common understanding of knowledge is that a person knows X (whatever X stands for) if that person has a true, justified belief about X. Justification refers to evidence. This traditional understanding of knowledge has been challenged on the grounds that you might have a justified true belief about X --that Pat Jones is in Spain-- and yet the justification / evidence is spurious, e.g. imagine you are seeing Jones' identical twin, Chris Jones, in Spain and you inappropriately conclude you are actually seeing Pat. This has caused some philosophers to amend the definition to: A person knows X if the person's belief is true and the evidence for this belief does not involve essential reasoning by way of a false premise. Matters that remain unsettled include (a) Just how much evidence or justification is needed for one's belief to count as knowledge,...

The topic of trust is very, very important on all sorts of levels, from everyday exchanges, to contributing to this website, to ordering food at a restaurant, signing a loan to buy a car....In fact, it may be that TRUST of some kind, even if it is the minimal sense of having to trust your own thinking, may play an important role in virtually all our waking hours. I will put to one side whether there is trust in dreams! First consider a few observations about what is trust... At least in English, the word trust may be used widely; I might trust my computer to work, trust that it will not rain when I have to work with the homeless this afternoon as part of a charity project, and so on, but I suggest that its principle use is in terms of persons. In this sense, when you trust someone or something someone has made, you are doing something more than RELYING on the person to be predictable or EXPECTING a persons work to function as it has in the past. Trusting my students or them...

Excellent question(s). I suggest that in some areas of historical inquiry, trusting the "cutting-edge experts" in philosophy makes a great deal of sense (though not always). So, when it comes to dating and reconstructing which of Plato's dialogues were early or late, or what is the best available translations of texts, and the tracing of influence (how many ideas of Hume's were novel), it seems quite reasonable to "trust the experts." I suggest, however, that trusting expert philosophers on history is tricky when it comes to issues in which one's philosophical convictions might color one's judgment. So, a philosopher who is disposed to distrust utilitarianism, might be led to judge that the reason why Moism in China failed was because of the inherent limitations of such an abstract form of ethical teaching, when in fact that was not the reason why Moism did not have a longer life span. Moreover, when it comes to philosophers making claims that impact our daily lives, it may be that they are no less...

There may be some difference insofar as a justified belief is usually considered a belief that is backed up by some evidence, and there may be times when it is rational (or not irrational or unreasonable) to have a belief even if one is quite uncertain about evidence. To use a homely example: You might have a vague feeling that you left your car keys back at the office and it would be rational for you to believe that is true (and go back to the office to check) even though your vague feelings don't count as sufficient evidence to make your belief fully justified. So, while there may be a difference, the two terms might be used interchangeably, especially if you hold what is sometimes called evidentialism, according to which the only beliefs that are rational and justified are those that you have evidence for. This is distinct from forms of what is sometimes called reliabilism, the view that a belief (even without evidence) may be justified if it is produced by a reliable means.

Thank you for these interesting reflections! As for your first point, there are a number of philosophers who address radical skepticism (e.g. can any of us know with certainty that we are not, as we seem to be, wide awake and acting in the world rather than, say, dreaming?) in the way you suggest. Arguably, life may continue just as it appears until one's death and yet there would be no decisive reason to rule out the possibility one was merely a brain in a vat. And because of this, some philosophers think that such radical skeptical hypotheses are idle or nonsensical or of no interest. I am somewhat of the other mind: I think we can imagine radical hypothetical states of affairs in which we are indeed systematically mistaken in almost all our beliefs about ourselves in the world (in brief, I think it conceivable that we might be in the matrix). While this does not have awesome practical consequences, I think it should humble us in our knowledge claims. As for the second point, Quine set out to...

While Ayer's verificationism has gone out of fashion (he and others could not settle on a formulation of it that did not rule out science or some such apparently meaningful discourse) there are forms of what is called anti-realism which define 'truth' in terms of warranted assertability, which would rule out the possibility of there being truths that are out of reach from what we can know (at least in principle). Alas, there is a good argument against such a position in Thomas Nagel's work The View From Nowhere. One other idea to consider is that your friend may be right but in a way that has nothing to do with THIS (our) world. Some philosophers (David Lewis etc) have argued that there are indefinitely many POSSIBLE WORLDS. So, you might reply that, yes, leprechauns actually do exist but in a possible world not remotely related to ours! Check out Lewis's book on the plurality of worlds. It is awesome.

There are a few points to consider: first, the challenge of understanding another's point of view. Second, knowing without any doubt whatsoever another's point of view. The later is sometimes connected with what philosophers call the problem of other minds or, more recently, it has been called the zombie problem. How do you know that all of those around you who appear to be thinking, feeling, conscious persons are actually mindful, conscious beings? Could they all be zombies? Few philosophers worry about this as a real possibility but there are philosophers who think that such a state of affairs is logically (or metaphysically) possible (however unlikely) and this leads them to certain conclusions in their philosophy of human nature (sometimes such thought experiments have been used to argue that consciousness is something more than anatomy and behavior). In any case, I suspect it would be quite rare to come across someone who could not understand the points of view of other people. If we were...

There are some philosophers who think that human observations will always be from some subjective point of view. Indeed, modern philosophers have often thought that the secondary properties of objects (how an object looks, what it smells like, for example) will reflect the cognitive powers of observers. And some philosophers known as nonrealists will claim that there is no unique, "objective" description of the world. The white room with the chair might be described in terms of room or chair parts or as filled with only a slice of the spatio-temporal object of the room. But many philosophers in the past and today think that observations can be fair, free of bias and what one might call objective. I am pretty much in the realist camp and believe that "banal statements" can be assessed in terms of truth or falsehood in a pretty problem-free fashion. The state of affairs of 'There being a white room with a chair in it' is something that one can see and confirm. The fact that the very notion of a chair...

Pray for them. Just kidding, though perhaps a prayer would not be uncalled for! I wonder if your friend is an extreme skeptic when it comes to empirical experience. Perhaps he is akin to Peter Unger in his book Ignorance, in which he seeks to undermine our confidence in our claims to know about ourselves and the world. Plato seemed to adopt a position not completely unlike your friend: he appers to have held that we may be more certain of the things of reason (mathematics, knowledge of the forms) than we can about the reliability of our senses. It is easy to have some sympathy with such an outlook: I am, for example, more convinced that 2+2=4 than I am convinced that I am not merely dreaming about the website AskPhilosophers. But your friend is in an usual position. Most of the philosophers who today defend the evidential role of religious (or spiritual) experience such as Richard Swinburne, William Alston, Jerome Gellman, Caroline Franks, K.M. Kwam, etc, argue for the reliability of such...