Lots of things should be said to exist, even though they are not material entities (like raindrops) nor energy forms (like sunlight). We're happy to talk about numbers or abstract concepts as existing, for example, and likewise dreams, or things that happened in the past. We might provisionally say that X exists if it were to matter in some way if someone asserted that X did not exist. (This is a pragmatist definition. I'm not endorsing it so much as finding it useful.) If someone said that you DID NOT have the dream last night you say you had, then that would matter, because they would be saying you are lying; if someone says that we have no concept of causation (Hume), then that matters because whole bits of philosophy, and maybe physics too, become valid or invalid. An optical illusion exists because its happening matters to the person experiencing it. (So, even an atheist would have to admit that God existed, because it matters so much to so many that he does; however, the atheist would assert...

Thank you for your question. Without a doubt, if you told David Hume that 'I am going to be tortured' he would respond 'For goodness sake, run!' The question is, then: is this response incompatible with his philosophical analysis of the concept of substance? I think we need to distinguish two ways of thinking about 'substance'. The first is substance as metaphysical, as something that exists permanently, without even the possibility of change, as the 'bearer' of properties (Hume has Descartes and Leibniz particularly in mind). The second is a pragmatic sense of substance, as our sense of the identity of things (including ourselves) across time. By pragmatic, I mean that for certain purposes we think of things as basically unchanging, while for other purposes we think of things as not unchanging. For example, if I buy a new car, I consider it unchanging for the purposes of driving every day, staying the same size, staying the same shape and colour. If, however, after a year I tried to return it to the...

Well, you raise a whole series of fascinating issues in your question. I'll just focus on the claim Heidegger makes, and not direct myself to either Fichte or Kant. What does Heidegger mean in claiming that the question of the meaning of Being has rarely if every been asked? I wouldn't say that he means that the question has been 'supressed' -- in the way free speech is supressed in a totalitarian regime. Rather, he means that the question has always been raised only with respect to some limited frame of reference, where that frame is determined by other philosophical commitments. A theological frame of reference understands Being only as either creator or created; the frame of reference of mathematics yields a conception of Being as substance; a technological frame of reference understands Being (including the human) only as the availability or otherwise of resources; and so forth. The other point worth making is that although the above discussion makes Heidegger sound as though he is...

Unfortunately, there is not one reasoning, since there are many different philosophers who have been called 'existentialists'. However, generally, the line of argument has to do with understanding the ontological differences between human beings and other types of beings. Other types of beings (a telephone, a piece of granite) may have essences -- definitions that determine the type of thing they are. And, there may be good reasons for thinking that a being cannot exist without an essence, without being the kind of thing that it is. (This is particularly clear in the case of manufactured entities.) However, there seems to be a difference with human beings. To be sure, all humans are of the type 'human', but morally and socially that doesn't tell us anything important about them. Instead, what seems most important to make up this human being's identity, to tell us what he or she is, are the sum total of that person's decisions. For that reason, existence precedes essence. In short, the...