Does an universal affirmative (A) premise entail a particular affirmative (I) one? I mean "All men are mortal" entails "Some men are mortal" or not? This is somehow confusing. Since, if you think that in a relation with set theory, it is impossible for (I) not to be entailed by (A). (A) intuitively entails (I). However, when looking at the opposition of square and applying, for example, tree method to prove the entailment, it results that (A) does not entail (I).

In Aristotle's syllogistic logic (including in his square of opposition), "All men are mortal" implies "Some men are mortal." But in the standard logic of the past 100 or so years, that implication doesn't hold. This failure of implication arises because modern standard logic construes "All men are mortal" as a universal quantification over a conditional statement: "For anything at all, if it's a man then it's mortal." Intuitively, I think we can see why the universally quantified statement can be true even if no men exist. Compare "For anything at all, if it's a unicorn then it's a unicorn," which seems clearly true despite the fact that (let's assume) no unicorns exist. In modern standard logic, then, "All men are mortal," "No men are mortal, " and "All men are immortal" come out true if in fact no men exist. Importantly, "Some men are immortal" does not come out true in those circumstances. A similar lesson applies in set theory, in which "All of the members of the empty set are even" and...

Many astrophysicists speculate that everything came from nothing. How can something come from nothing? The above speculation would break the law of conservation. Either something has always been here or what we call something is actually made of nothing (nonmaterial.) Please give me your prospective. Thank you, Awareness1963

My perspective: Even if matter hasn't always existed, something or other has always existed (which is compatible with the claim that our Big Bang occurred finitely long ago). For the perspective of someone much better-informed about this issue than I am, see this link .

For the record, I'm far from happy with Krauss's way of putting things, which is why in my response I linked not to Krauss's book but to Albert's (scathing) review of it, the same review later linked to by Professor Stairs.

In an answer to a question, Stephen Maitzen wrote, "if one's argument depends on controversial premises, then one ought to improve the argument by finding less controversial premises that imply one's conclusion." Am I mis-reading what he wrote? Does it come across to others as "one starts with the desired conclusion and then works backwards to develop premises that would support the desired conclusion." ? There may be evidence from recent psychological studies (e.g., Kahneman's Thinking Fast and Slow that indicate that our minds actually do work in this manner. However, I was under the impression that philosophers generally reason by starting with premises that seem reasonable, and then using logic to determine where those premises lead. His statement perhaps indicates a different path.

Thanks for the chance to clarify my answer to Question 25338 . I can see how my answer might have given the wrong impression. I didn't mean to suggest that, whatever one's desired conclusion, one can always find less controversial premises that imply it. That is, one may fail in the attempt to improve one's argument, no matter how hard one tries. One's conclusion may just not follow from less controversial premises. My point was simply that a logically valid argument from less controversial premises to conclusion X is better than a logically valid argument from more controversial premises to conclusion X. It's something one should strive to find, even though there's no guarantee of success, and failing to find it may be a good reason to reconsider one's conclusion.

First of all, I'd like to express my personal thanks for having this resource online. I'm having difficulty understanding the distinction between metaphysical possibility and logical possibility. It is said that Kripke's example, "Water is H2O" is an example of a metaphysically necessary truth, but not a logically necessary one. However, to me it seems that the extension of the terms "water" and "H2O" is the same, so the meaning of the statement is of the form A is A. (Isn't it with the meaning of a statement that logic is concerned, and not whichever semantically equivalent terms are used?) Isn't the statement that A is A logically necessary? A world where A is not A seems to be a violation of the law of identity. I guess it's likely that I am wrong. What are my mistakes? Thanks again.

Interesting question! First, I should note that some philosophers object to the claim that the ordinary term "water" refers to the chemical kind H2O. See here and here . Just for simplicity, my answer will ignore their objections. Second, a point about form. Using italics for propositions, I think we should replace the proposition Water is H2O with the universally quantified proposition Whatever is water is H2O , because, as I see it, the first proposition is false in all those possible worlds in which water doesn't exist, whereas the second proposition is (vacuously) true even in such worlds. Likewise, as I see it, the proposition Pegasus is Pegasus is contingently false (there being, as a matter of contingent fact, no such thing as Pegasus), whereas Whatever is Pegasus is Pegasus is necessarily true. So, on this view, the law of identity has the form "Whatever is A is A." I'd say that the important difference between Whatever is water is H2O and Whatever is A is A isn't...

My question relates to reclusive behavior. I wish not to be active socially because it requires so much time and I seem not to learn or be entertained by the contact with others. I am 83 years old and was a medical sales person throughout most of my life. I am a widower. Most of my time is spent on the internet learning things I have wondered about throughout life. My question is: Do very socially active people have less interest in learning things they do not know or do they already know or understand all that they ever wondered about. All information that may be provided regarding my inquiry will be appreciated.

The reclusive behavior you describe will be familiar to many philosophers! The great Scottish philosopher David Hume (1711-1776) famously wrote that socializing with friends helped him escape from his philosophical brooding when he felt overwhelmed by it. But thank goodness for his philosophical brooding! Otherwise he'd have been a much less important contributor to human civilization. You've asked a psychological question, really, so I'm not equipped to answer it, but the list of philosophers who have preferred thinking over socializing is long and illustrious. I'd recommend that you look for psychological literature that discusses the personality traits of introversion and extroversion and their characteristics. If you should discover that extroverts typically "have less interest in learning things" or believe "they already know or understand all that they ever wondered about," then how sad for them. Keep inquiring!

In his TV series "Genius," Stephen Hawking presented an experiment in which people decided to push a button in order to stop a rotating dial. They were hooked up to EEG at the time. The experiment indicated that people decided to push the button, and then about 1 second later they became aware that they made this decision. Hawking, however, interpreted the evidence differently. He claimed that people's "unconscious" mind made the decision. It seemed to me that Hawking made significant logical error: he conflated "consciousness" with "self-awareness." It seems quite clear (at least from anecdotal reports from people who have been in a life-threatening situation) that our conscious minds are capable of processing information and reacting to it with extraordinary quickness. it also seems that we would be at a serious selective disadvantage if we were self-aware during these episodes. Is this distinction "merely" a matter of semantics? In Hawking's show, it seemed like he was interpreting data in a...

Your question raises a number of philosophical and scientific issues. You'll find them expertly discussed in this short and reasonably priced book by Alfred R. Mele, one of the world's leading authorities on the topic: Enjoy.

One major problem I have with a lot of arguments is that at least one premise relies on intuition to be justified. The problem is that intuition is terribly unreliable and therefore cannot be used to justify a premise. Arguments that rely on intuition seem common in normative ethics from my what I have seem (The utility monster is one such example). I decided to make a thought experiment to tell if the argument relies on intuition that goes like this: You are alien which is born with the intuition that utilitarianism and is self-evident You discover a planet and decide to go visit it to find people living on it. you ask a person about utilitarianism and the person think it is false and use the utility monster argument to back up that assertion. Would you think this argument is sound or even makes only sense or a actual problem with the position you think is self-evident? Utilitarianism can be changed to whatever the position be attacked is and the utility monster into the argument against said...

It's hard to see how any thought experiment could be good for filtering out all intuition-based arguments, for the simple reason that one's reaction to any thought experiment is itself a matter of one's intuitions. In your own thought experiment, I'm supposed to imagine how I'd react to the utility-monster objection if two non-actual conditions held: (1) I'm an alien, and (2) I'm born with the intuition that utilitarianism is self-evident. To be honest, I have no idea how I'd react under those conditions, but the only thing I can consult to answer the question would be my intuitions about the imagined case. Any (finitely long) argument, including any sound argument, will rely on intuitions in the sense that it will contain premises that the argument simply asserts and doesn't defend. That being said, if one's argument depends on controversial premises, then one ought to improve the argument by finding less controversial premises that imply one's conclusion.

Regarding the age old conundrum of the tree falling in the forest. According to Barclay, there is no sound if there is no mind to hear it. I am thinking that there may be no human around hence no human auditory organs to absorb the waves and send the message of "sound" to the brain.....but that is a bit anthropocentric. The forest is full of creatures that have auditory organs, so some brains will hear the sound....some minds will perceive the sound of a crashing tree, no? (listening to Nigel Warburton's A Little History of Philisophy)

I agree. I don't know what Berkeley says about whether any nonhuman animals possess minds, but on his view, I take it, nonhuman animals would need to possess minds in order to perceive anything. Indeed, according to Berkeley, not only does the tree make no sound unless a mind perceives the sound, but the tree doesn't even exist without a mind to perceive it. (Even if no finite mind perceives the tree, Berkeley attributes the tree's existence to the tree's being perceived by God's mind.) Notice, too, that if we construe "a sound" dispositionally, i.e., as simply a disturbance that would be heard if there were a normally equipped listener to hear it, then sounds can occur even with no listeners (human or nonhuman) on the scene.

Person A receives a large amount of money. Being selfless, he doesn't want to keep the money and sends it to person B. Unfortunately, B is also selfless, and sends the money back to A. A then sends the money to C. Fortunately, C is selfish and keeps the money. Can there be selflessness without there being selfishness?

I think so. Consider the example you gave. A's selflessness (her generosity, anyway) is manifested by her sending the money to B, whether or not B ends up accepting the money. Now, if A somehow knows that B will return the money immediately and is counting on B to return it, then A's selflessness is only apparent rather than genuine. But otherwise, I see no reason why A's action can't be considered genuinely selfless, whether or not the recipient in fact keeps the money. Further, I see no reason why C must be deemed selfish just because he accepts the money: it might be that, through no fault of his own, C desperately needs the money. What I think genuine selflessness does require is scarcity: if a particular resource is available to all in unlimited supply, then no one can genuinely make a gift of that resource, let alone a selfless gift. So I don't think there can be selflessness in heaven, if heaven is as it's described by various religions.