In my amateur philosophy club, my friend told me that modal ontological argument is false because its premise, It's possible that a perfect being exists, doesn't make sense. He argued that it is logically equivalent to say "it is possible that it is necessary", which means 'there exists at least one possible world in which all possible worlds have this objects in them.' So, according to his analysis, that premise make possible worlds in a possible world, which is absurd and makes a danger of infinite regress. But I think he misunderstood the argument. I think what actually that premise says is "there is at least one possible world that has a object which is in every possible world." I think this is implied when the argument says that "if something possibly necessarily exists, then it necessarily exists." Am I wrong?

Excellent question. It's great to hear that you belong to a philosophy club. As I see it, if the modal-ontological argument fails, it's not because the locution "It is possible that it is necessary" is absurd or ill-formed or meaningless. The opening premise of the modal-ontological argument can be expressed without using the possible worlds idiom: There could have been a necessarily existing God (where "could have been" is construed as consistent with "is"). The idea is that even atheists are supposed to concede that a necessarily existing God is at least logically possible: logically speaking, there could have been such a thing (even if, according to atheists, there isn't). Granted the possibility of a necessarily existing God, the argument then uses the modal principle "If it's possible that it's necessary that G, then G," letting "G" in this case stand for the proposition that God exists. Conclusion: God actually exists. In my view, the argument can be challenged for assuming (1) the above...

Some people define some things (which they truly may be or are) Impossible. 'Impossible' has a humane meaning in itself. But... If 'something' is really impossible... then why can you think that? If something is impossible... then why did the neurons in your brain have that thought? It must've been impossible for them to think of something which is not possible.

I'll assume, just for simplicity, that by a "thought" you mean a belief and by "something impossible" you mean a proposition that cannot possibly be true . I hope my assumptions aren't off the mark. (I'm not a neuroscientist, so I'll say nothing about how neurons work.) If my assumptions are correct, then your question becomes "How can anyone believe a proposition that cannot possibly be true?" One answer is this: "Easy! For example, many people down through the ages believed that they had accomplished the famous geometric construction known as squaring the circle . But the proposition they believed cannot possibly be true, because squaring the circle is impossible, as was finally proven in 1882. Those who believed the proposition obviously didn't see the impossibility of the construction." An opposing answer is this: "They can't! Indeed, we can understand the behavior of those misguided geometers only if we attribute to them a false belief that could have been true, such as the belief that a...

If humans are just a bunch of extremely complicated gears working together, how can we have self-awareness?

Short answer: Because some bunches of extremely complicated gears are capable of self-awareness. Longer answer: We need to ask whether the reductive term "just" in your question makes the question tendentious (i.e., biased). To the question "If humans are just like the non-self-aware bunches of gears that we understand best -- such as the bunch of gears in a clock -- then how can they be self-aware?" the answer is clearly "They can't." But the latter question isn't interesting, so presumably it's not the question you intended to ask. To put it another way, humans can be bunches of gears (using "gears" only metaphorically) without being merely bunches of gears. It could well be that when a bunch of gears gets complicated enough, it becomes capable of self-awareness. Exactly how that happens is a question for neuroscience rather than for philosophy.

I suppose it is very difficult do define "truth" in an informative way (without just giving a synonym or something like that). Can you explain why it is so? Or is it easy?

One reason that it's difficult to define "truth" might be that the word stands for a concept that's too basic, too fundamental, to be informatively defined in terms of other concepts. I myself think that truth is a property of some propositions and therefore, derivatively, a property of some sentences. Which propositions? The true ones! Which sentences? The ones that express true propositions! The proposal that we can't say more than that is sometimes known as "deflationism" about truth. For much more, see this SEP entry .

Is there really a strong distinction between understanding what a proposition means and believing or disbelieving it? It strikes me that if I believe a proposition while my opponent does not, one way to explain the disagreement is to say that he misunderstands either that proposition or some related proposition. And so if we really did both understand all of the propositions in question, we'd have to agree about them as well.

I'd say that in many cases there's indeed a difference between grasping a proposition and believing the proposition, i.e., believing it to be true. To take a well-known example from mathematics, Georg Cantor believed that the Continuum Hypothesis is true, whereas Kurt Gödel believed it's false. Both were brilliant mathematicians; I see no reason to think that their disagreement arose from either man's misunderstanding the proposition in question or some related proposition. But not all cases are like that. Consider the proposition that all bachelors are unmarried. Anyone who fails to believe that proposition, I'd say, fails to grasp it, because grasping the proposition implies believing the proposition. At any rate, I can't make sense of the idea that someone could grasp that proposition without believing it.

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!