Advanced Search

We know for now, at least, it's impossible to go back in time scientifically.

We know for now, at least, it's impossible to go back in time scientifically. But what if you really needed to, say if you had done something really bad and had ever desperation to go back in time and correct what you did, so you don't suffer the consequences you are suffering in the present. Provided you would not cause a disaster by going back in time, and that you would only change the bad things you did, it is an interesting concept. With this context, if you could be given a drug, that would leave you asleep for the rest of your life (coma), would you do it? Read on, there's more. In this sleep, you will have a dream, which is set from just before your mistake. So essentially, it causes you to simulate the past and the rest of your life in your head. It seems real, but it isn't. My question is, would this be the same as going back in time and changing things in reality? Does reality matter more, or our interpretation of it?

First a terminological quibble. By "scientifically impossible," I take it you mean "technological infeasible," i.e., impossible given the limits of current technology. As I see it, what's scientifically possible or impossible depends only on the laws of nature, which are standardly taken to be unchanging over time (or at least over any time that humans will experience). I think the jury's still out on whether backward time-travel is scientifically impossible in this latter sense.

To your question: I think there's something self-contradictory in the idea of "correcting what you did" if that means "bringing it about that you never did what you in fact did." Either (1) you did it, or (~ 1) you never did it. I can't see how any consistent story features both (1) and (~ 1).

In that sense, then, there's no such thing as (2) "going back in time and changing things in reality" and therefore nothing that's the "same as" (2). See section 1.2 of the SEP article on time-travel.

First a terminological quibble. By "scientifically impossible," I take it you mean "technological infeasible," i.e., impossible given the limits of current technology. As I see it, what's scientifically possible or impossible depends only on the laws of nature, which are standardly taken to be unchanging over time (or at least over any time that humans will experience). I think the jury's still out on whether backward time-travel is scientifically impossible in this latter sense. To your question: I think there's something self-contradictory in the idea of "correcting what you did" if that means "bringing it about that you never did what you in fact did." Either (1) you did it, or (~ 1) you never did it. I can't see how any consistent story features both (1) and (~ 1). In that sense, then, there's no such thing as (2) "going back in time and changing things in reality" and therefore nothing that's the "same as" (2). See section 1.2 of the SEP article on time-travel .

Do most philosophers take the Paul and Patricia Churchland's eliminative

Do most philosophers take the Paul and Patricia Churchland's eliminative materialism seriously? I'm concerned about the current state of philosophy of mind in that it seems that at least some people take seriously the suggestion that e.g. beliefs don't exist (and that they are believed in in a theoretical manner). So, again, how popular is the Churchland's eliminative materialism in contemporary philosophy of mind?

I'm not sure why you regard it as a worrisome sign about current philosophy of mind that some of its practitioners take eliminative materialism (EM) seriously. At worst, it would show that some philosophers regard EM as far more plausible than it really is, but even then I don't see how that would indict current philosophy of mind as a whole.

Anyway, you've asked an empirical question whose answer depends on (1) reliable data about the views of philosophers and (2) what you mean by "take seriously." I presume you mean something like "regard as too plausible to be dismissed without argument," which is a weaker attitude than "regard as plausible." I don't have empirical data, but my hunch is that most philosophers do take EM seriously in that sense, but probably because most philosophers don't regard any philosophical position as worthy of being dismissed literally without argument. At the same time, however, my hunch is that most philosophers regard EM as implausible.

Curiously, the PhilPapers Survey doesn't ask about attitudes toward EM, although it does ask about attitudes toward other positions in philosophy of mind. One might conclude that the survey organizers didn't regard EM as worth asking about, which might reflect the organizers' own hunch about the popularity of EM, but they do ask about several philosophical positions that garner the support of only a tiny minority (3% or so) of those surveyed. So I don't know what to conclude about the omission of EM from the list.

But far more important than the actual distribution of views about EM are the arguments for and against it. About those, see this SEP entry.

I'm not sure why you regard it as a worrisome sign about current philosophy of mind that some of its practitioners take eliminative materialism (EM) seriously. At worst, it would show that some philosophers regard EM as far more plausible than it really is, but even then I don't see how that would indict current philosophy of mind as a whole. Anyway, you've asked an empirical question whose answer depends on (1) reliable data about the views of philosophers and (2) what you mean by "take seriously." I presume you mean something like "regard as too plausible to be dismissed without argument," which is a weaker attitude than "regard as plausible." I don't have empirical data, but my hunch is that most philosophers do take EM seriously in that sense, but probably because most philosophers don't regard any philosophical position as worthy of being dismissed literally without argument. At the same time, however, my hunch is that most philosophers regard EM as implausible. Curiously, the PhilPapers...

There has been much made of Hawking and Harris using brain scans to demonstrate

There has been much made of Hawking and Harris using brain scans to demonstrate a deterministic explanation of "free will". My question is, how do they treat a case where I think about moving my arm, but don't? How can the experiment they site test thoughts, subjective experience, etc. which do not lead to any outward physical effects? Must we accept that for all cases of mental phenomena that the brain scan test constitutes a proof?

Must we accept that for all cases of mental phenomena ... the brain scan test constitutes a proof?

I think the important philosophical question here is "A proof of what?" Suppose that science did somehow establish that all of our choices are causally determined by our earlier brain states. According to compatibilism, that result wouldn't threaten free will at all, and according to many compatibilists it would be good news indeed for free will. Before we get too hung up on whether brain scans are evidence in favor of determinism about human choices, let's ask the prior philosophical question "What difference would that make for free will?" You'll find this issue discussed many times on this website, including here:

Question 5451
Question 5711

Must we accept that for all cases of mental phenomena ... the brain scan test constitutes a proof? I think the important philosophical question here is "A proof of what?" Suppose that science did somehow establish that all of our choices are causally determined by our earlier brain states. According to compatibilism , that result wouldn't threaten free will at all, and according to many compatibilists it would be good news indeed for free will. Before we get too hung up on whether brain scans are evidence in favor of determinism about human choices, let's ask the prior philosophical question "What difference would that make for free will?" You'll find this issue discussed many times on this website, including here: Question 5451 Question 5711

Is mathematics independent of human consciousness?

Is mathematics independent of human consciousness?

I'm strongly inclined to say yes. Here's an argument. If there's even one technological civilization elsewhere in our unimaginably vast universe, then that civilization must have discovered enough math to produce technology. But we have no reason at all to think that it's a human civilization, given the very different conditions in which it evolved: if it exists, it belongs to a different species from ours. So: If math depends on human consciousness, then we're the only technological civilization in the universe, which seems very unlikely to me.

Here's a second argument. Before human beings came on the scene, did the earth orbit the sun in an ellipse, with the sun at one focus? Surely it did. (Indeed, there's every reason to think that the earth traced an elliptical orbit before any life at all emerged on it.) But "orbiting in an ellipse with the sun at one focus" is a precise mathematical description of the earth's behavior, a description that held true long before consciousness emerged here. Kepler may have discovered that description, but the truth of the description predated him and every other human. So at least one true mathematical description is independent of human consciousness.

Here's a third argument. If the answer to your question is no, then there were zero mathematical truths before human beings came along, in which case there weren't more than zero mathematical truths. But the fact that zero isn't more than zero is a mathematical truth. So there couldn't have been zero mathematical truths. So the answer to your question couldn't be no.

I'm strongly inclined to say yes . Here's an argument. If there's even one technological civilization elsewhere in our unimaginably vast universe, then that civilization must have discovered enough math to produce technology. But we have no reason at all to think that it's a human civilization, given the very different conditions in which it evolved: if it exists, it belongs to a different species from ours. So: If math depends on human consciousness, then we're the only technological civilization in the universe, which seems very unlikely to me. Here's a second argument. Before human beings came on the scene, did the earth orbit the sun in an ellipse, with the sun at one focus? Surely it did. (Indeed, there's every reason to think that the earth traced an elliptical orbit before any life at all emerged on it.) But "orbiting in an ellipse with the sun at one focus" is a precise mathematical description of the earth's behavior, a description that held true long before consciousness emerged here....

Hi,

Hi, I'll just share my experiences as below and would just like to ask what principle or theory that could possibly explain the phenomenon? And what term you call it? I'm a computer programmer. Sometimes there are program logic related problems that I was trying to solve for hours, and yet cannot figure out the answers. But when I ask a colleague regarding the problem, in an instant, even before my colleague answers my question, I was able to draw the answer from my mind. Then, I'm going to tell my colleague, "uhm, ok, I know already! Thanks". It always happen. Sometimes, just the presence of another person would help you to resolve your problem.

You have described a fascinating phenomenon that I think is remarkably common, though I don't agree that it always happens It certainly happens frequently in my experience. Perhaps we both have very bright colleagues whom we happen to know very well, and can anticipate what they will say! I am delighted to see "the phenomenon" so well described. However, in the form you present it, I think most philosophers and psychologists would say that the question you ask is a psychological one, not a philosophical one, and that no doubt it is amenable to empirical research. Still, it does prompt a philosophical thought or two. I am put in mind of Wittgenstein's observation that 'In philosophy it is not enough to learn in every case what is to be said about a subject, but also how one must speak about it. We are always having to begin by learning the method of tackling it.' Perhaps when you ask a colleague about your problem, you have to decide not just what to say but how to say it, and that is enough for your mind to turn up the answer. This is true in philosophy, but perhaps if the problem is one whose shape is completely obscure to you, it is in effect a philosophical problem for you, at least temporarily. Then you see the way through the confusion to what is actually going on. I wonder what sort of experiments a psychologist might suggest to answer your question, 'What principle could explain the phenomenon?' I am sure there are bad philosophical principles that some people would drag in, such as this: you already knew the answer in a previous life (Plato). I would go very gingerly with answers like that.

Interesting, but it's an empirical, psychological question rather than a philosophical question properly so-called. I therefore recommend asking a psychologist or looking into the psychology literature. Any philosopher who tries to answer it is doing psychology, and probably from his/her armchair.

The universe appears to behave in logical ways. All of the individual physical

The universe appears to behave in logical ways. All of the individual physical components of the universe, as far as we can tell, are likely governed by logically consistent laws of physics. According to physicalism, human beings are nothing more than complex physical systems. That means that the physical components and functions of a human being, including those that give rise to human thought, are governed by the same logically consistent laws that govern the behavior of electrons, etc. If the physical processes that give rise to thought are rational how can a human being have an irrational thought? Where in the system does irrationality arise? It seems that human beings are in fact capable of irrational thought. If two people hold mutually exclusive ideas then at least one of them must be wrong. But if irrational thought is possible where does it come from? Is this an argument against physicalism? Does it mean we are more than just bits of matter? Or does it mean that the universe itself doesn't...

You asked, "If the physical processes that give rise to thought are rational, how can a human being have an irrational thought?" You might be misinterpreting the claim that "the physical processes...are rational." Presumably what's meant by the claim is that the physical processes can be discovered and understood by rational means, such as empirical investigation and logical reasoning. The claim doesn't mean to attribute rationality to the physical processes themselves: the processes don't literally investigate or reason, either well or badly. So the fact that the physical processes can be discovered and understood rationally doesn't imply that irrational thoughts can't result from those processes. Furthermore, we can rationally investigate the physical causes of irrational thoughts, even if science isn't very far down that road at present. In any case, we should resist the suggestion that the universe sometimes violates the laws of logic: that suggestion is either impossible or not even intelligible.

You asked, "If the physical processes that give rise to thought are rational, how can a human being have an irrational thought?" You might be misinterpreting the claim that "the physical processes...are rational." Presumably what's meant by the claim is that the physical processes can be discovered and understood by rational means , such as empirical investigation and logical reasoning. The claim doesn't mean to attribute rationality to the physical processes themselves: the processes don't literally investigate or reason, either well or badly. So the fact that the physical processes can be discovered and understood rationally doesn't imply that irrational thoughts can't result from those processes. Furthermore, we can rationally investigate the physical causes of irrational thoughts, even if science isn't very far down that road at present. In any case, we should resist the suggestion that the universe sometimes violates the laws of logic: that suggestion is either impossible or not even...

Do you think that there are things humans cannot understand because our brains

Do you think that there are things humans cannot understand because our brains are limited? Philosopher Thomas Nagel was recently quoted as saying that there are surely truths that people cannot understand (and will never be able to understand), as "nine-year olds cannot understand Maxwell's equations". I don't think this is a good example: after all nine-year olds are very smart, and it seems to me that they just don't have the time and information to "understand Maxwell's equations" while they are still nine years old. Is there any reason why nine-year olds wouldn't understand those equations if they had a nine-year old brain (physically speaking) forever (always adding new information)? And what if such equations were explained to them? Anyway, I would like you to answer not about the example, but about the general issue. Of course there are things we will never know and cannot know (for instancel, many things that happened before humans existed, or in distant parts of the universe, or things people...

I'm inclined to think that there are, and perhaps must be, things that humans can't understand because of the limitations of our brains. Now, the term 'understand' might mean (i) 'understand at all (i.e., at least partly)' or (ii) 'understand completely'. On interpretation (ii), it's pretty clear that there are things we can't understand, because our finite brains can't grasp all of the infinitely many facts there are about even as ordinary a thing as my car. What's my car's exact mass right now? (No rounding allowed!) Even on interpretation (i), there may be things that humans can't understand.

The only organ with which we can hope to understand something is our brain. Why wouldn't our brain's finite capacity for information storage, calculation, and so on, be accompanied by a finite capacity for understanding things? Indeed, Colin McGinn has conjectured that some of the central problems of philosophy have endured for so long because, although they have solutions, our species lacks the ability to understand those solutions. See his Problems in Philosophy and this later paper. Jonathan Bennett sounds a similar theme in his article 'Descartes's Theory of Modality', Philosophical Review 103 (1994): 639-667, at 656.

I'm inclined to think that there are, and perhaps must be, things that humans can't understand because of the limitations of our brains. Now, the term 'understand' might mean (i) 'understand at all (i.e., at least partly)' or (ii) 'understand completely'. On interpretation (ii), it's pretty clear that there are things we can't understand, because our finite brains can't grasp all of the infinitely many facts there are about even as ordinary a thing as my car. What's my car's exact mass right now? (No rounding allowed!) Even on interpretation (i), there may be things that humans can't understand. The only organ with which we can hope to understand something is our brain. Why wouldn't our brain's finite capacity for information storage, calculation, and so on, be accompanied by a finite capacity for understanding things? Indeed, Colin McGinn has conjectured that some of the central problems of philosophy have endured for so long because, although they have solutions, our species lacks the ability...

What, if anything, can it possibly mean to deny the existence of the soul--the

What, if anything, can it possibly mean to deny the existence of the soul--the one and only thing that we have direct experience of? I can see why someone might deny the existence of a physical universe: we can only experience it as part of the content of consciousness: that is, of the soul. And I can understand why one might question some aspect of the soul: is it material or immaterial, mortal or immortal. But I don't see how one can question its existence without making use of the very thing they're questioning. To deny the existence of the soul seems to require some special definition of "soul"--but what? What is being asked when questions of the existence of the soul are raised? monk Herman Hanover, NM

From what I can gather, you're treating 'consciousness' as synonymous with 'soul'. You write, "as part of the content of consciousness: that is, of the soul." But 'soul' is a much more loaded term than 'consciousness': people tend to use 'a soul' or 'the soul' to denote a metaphysical substance, as Descartes did, whereas they tend to use 'consciousness' to denote an activity, a property, or a state of some substance, even if the substance is a material one. So I think it's better to use the less loaded term 'consciousness' when talking about what it is that we directly experience.

I agree that it's hard to deny the existence of one's own consciousness, but there are philosophers who (claim to) deny it. They're discussed in this entry from the SEP (see especially section 3.3). It's a challenging article but worth the effort, I believe. I hope it's helpful. But let me emphasize that one can accept the existence of one's own consciousness without accepting the existence of what's usually meant by 'one's soul'.

From what I can gather, you're treating 'consciousness' as synonymous with 'soul'. You write, "as part of the content of consciousness: that is, of the soul." But 'soul' is a much more loaded term than 'consciousness': people tend to use 'a soul' or 'the soul' to denote a metaphysical substance , as Descartes did, whereas they tend to use 'consciousness' to denote an activity , a property , or a state of some substance, even if the substance is a material one. So I think it's better to use the less loaded term 'consciousness' when talking about what it is that we directly experience. I agree that it's hard to deny the existence of one's own consciousness, but there are philosophers who (claim to) deny it. They're discussed in this entry from the SEP (see especially section 3.3). It's a challenging article but worth the effort, I believe. I hope it's helpful. But let me emphasize that one can accept the existence of one's own consciousness without accepting the existence of what's...

Although societal pressures do play a role, does atheism manifest itself mostly

Although societal pressures do play a role, does atheism manifest itself mostly due to an inborn lack of religious "sense" rather than hearing the logical arguments against God or a life force? Research has shown that autistic people are very unlikely to be religious. I don't know what phrase philosophers of mind use to describe this, but when we talk about people with a strong sense of humor, people with a weak sense of humor, or people with no sense of humor at all, are we talking about a non-physical and antimaterialist noumenon that can be enhanced with training?

I'll chime in just to say that the first question you asked is an empirical question and therefore not the kind of question that philosophers as such are any better-equipped than non-philosophers to answer. I'd be interested in seeing the empirical data myself. I would say, however, that your first question leaves out a possibility that strikes me as more plausible than the two you mention: as they grow and develop, children tend to imitate their parents and other authority figures, including in their attitudes toward religious matters.

I'll chime in just to say that the first question you asked is an empirical question and therefore not the kind of question that philosophers as such are any better-equipped than non-philosophers to answer. I'd be interested in seeing the empirical data myself. I would say, however, that your first question leaves out a possibility that strikes me as more plausible than the two you mention: as they grow and develop, children tend to imitate their parents and other authority figures, including in their attitudes toward religious matters.

I have been reading a recently published book about the existence of all things

I have been reading a recently published book about the existence of all things (e.g. addressing the question, "Why is there something rather than nothing?"), and am struck by an interesting issue I see in the book and others like it. The author interviews philosophers (among other professionals) who often speak about the existence of things based on what one can imagine (e.g. one imagining something about possible worlds). It seems to me that there should be some kind of theory about how thoughts relate to the universe before anyone can conclude things about its nature. I know there are philosophers who have raised the question that the "laws" that govern thought/logic may be very different than the physical laws that govern the universe (and hence whatever theories we have about the world may be nothing more than our own ideas); so why is there such emphasis placed on imagination when discussing metaphysical issues? Why is the intelligibility of an idea about the universe (e.g. whether there are many...

You asked, among other things, "Why is the intelligibility of an idea about the universe...a criterion for determining the truth-value of the idea?" I wouldn't say that an idea's being intelligible to us is a criterion for its being true: that would be thinking too highly of ourselves! But an idea's being intelligible to us is necessary for our determining (i.e., ascertaining) its truth-value and even for our entertaining the possibility that it's true. If an idea is unintelligible to us -- if we can't make any sense of it -- then we can't make sense of the assertion that the idea is true, or even possibly true, or false, or even possibly false. I think we can understand the claim that some unspecified aspects of reality are unintelligible to us. But we can't understand the suggestion that some particular unintelligible claim about reality might be true (or false, for that matter). That limitation applies to science just as much as to philosophy.

I suspect that the book you're reading is Jim Holt's Why Does the World Exist? If you're interested in a more scholarly approach to the question "Why is there something rather than nothing?" you might check out Tyron Goldschmidt's edited collection of essays, The Puzzle of Existence (Routledge, 2013). For what it's worth, I think the question is defective when construed in the way it's typically intended, as I try to show in my contribution to the collection.

You asked, among other things, "Why is the intelligibility of an idea about the universe...a criterion for determining the truth-value of the idea?" I wouldn't say that an idea's being intelligible to us is a criterion for its being true: that would be thinking too highly of ourselves! But an idea's being intelligible to us is necessary for our determining (i.e., ascertaining) its truth-value and even for our entertaining the possibility that it's true. If an idea is unintelligible to us -- if we can't make any sense of it -- then we can't make sense of the assertion that the idea is true, or even possibly true, or false, or even possibly false. I think we can understand the claim that some unspecified aspects of reality are unintelligible to us. But we can't understand the suggestion that some particular unintelligible claim about reality might be true (or false, for that matter). That limitation applies to science just as much as to philosophy. I suspect that the book you're reading is...

Pages