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Isn’t it true that ultimately all truth is conventional? The system of logic,

Isn’t it true that ultimately all truth is conventional? The system of logic, our inferences we accept, our physics, our views on reality; are all grounded in our presuppositions? To be intellectually honest there is no argument for objectivity. We have to retreat to commonsense realism and agreement among people and truth in reality is a matter of consensus! Even though none of us wishes to cop to that label. So logic, physics, science is all rhetoric or the art of convincing one of our views? Even if we hold that there is one God and His truth is absolute and objective - this is still a convention one must accept?

The way you begin your question hints at a problem we'll get to below, but before that, let me suggest a distinction. It's one thing to presuppose or assume something; it's another thing for it to be a matter of convention.

There's a lot to be said on the matter of convention; there's not just one idea under that umbrella. But let's take an example from philosophy of space and time. Adolph Grünbaum argued many years ago that given our usual view of space and time, lengths are a matter of convention. The gist of the idea was this: if space and time are continuous, then any two lines contain the same number of points. In Grünbaum's view, that meant there is nothing in space and time themselves to ground the difference between different possible standards for assigning lengths. We have to pick one (think of it as deciding what counts as a ruler) and only after we've done that do questions about lengths have answers. If Grünbaum were right (I'm not convinced, but that's not our issue), then there would be no hard fact of the matter about whether two non-overlapping lines have the same length. There would be no such fact because there'd be nothing in the world to ground it. But notice: Grünbaum's argument has nothing to do with what we presuppose or assume. It's an argument about how much structure the world really has. Grünbaum believed that it's not a matter of convention whether space and time are continuous. That's a fact about the world itself.

You might ask how we could know such a thing. That's a perfectly good question, and it might not be easy to answer. Furthermore, at some point in sorting out our beliefs, we'll have to assume that some things are true without being able to prove them (otherwise we end up in circularity or regress.) But whether I assume something without proof and whether it's true aren't the same question. (And for that matter whether I assume something without proof and whether I know it aren't the same thing. Knowing might be a matter of being connected to the facts in a reliable way. I could be connected that way whether or not I could prove it.)

This might be a good time to have a look at the way you pose your question: "Isn’t it true that ultimately all truth is conventional?" Unless I'm missing something, you're trying to show that it's true, full stop, that all truth is conventional; not that this is a convention we adopt (after all, we don't) nor something that we assume or presuppose (on the contrary: most people assume no such thing) but that this is how things really are. But if that's right, then there's at least one truth that isn't merely conventional. And in that case, the claim that all truths are conventional is false.

This might seem trivial; I don't think it is. Radical conventionalism is a thought we don't have a way to think. Once that's clear, you might start to suspect that there's a good deal more in the way of truths that we don't make.

People suppose that hard science is more objective than other subjects such as

People suppose that hard science is more objective than other subjects such as psychology. But doesn't science require good instincts, judgment, and intuition like any other field does? People say well all the scientists agree that global warming will have a big impact on the world but how can I really be so sure that it's as simple as "science sees it some way so it must be correct?" Isn't it just an unfounded prejudice that scientific judgements can be validated in some essentially simple and uncomplicated way?

You are asking a few questions here. One is whether you should take it on trust (or authority) that scientists are in agreement on a scientific questions such as global warming. Another is whether or not assessing scientific evidence is "simple" (and I think you are right in suggesting that it is not simple). And a third is whether or not science is "objective" (a complicated question that philosophers of science, as well as scientists, often debate). A final question you may be asking is whether physics or climate science is more "objective" or "simpler" than psychology or other social sciences, again a complicated question that there is no general agreement on.

Is human nature the subject of philosophy, or of the empirical sciences?

Is human nature the subject of philosophy, or of the empirical sciences?

I myself am inclined to think that both philosophy and (certain) empirical sciences--including psychology--investigate human nature, although they investigate it in different ways. For example--and oversimplifying--the genetic differences between human beings and other animals can be investigated by biology; philosophy, however, can investigate whether there is some ultimate, natural end that all human beings seek, a question that does not seem to me to admit of resolution by natural science but squarely to fall within the province of philosophy. (Aristotle, for example, claims that 'all men by nature desire to know': I do not think that this claim admits of empirical confirmation or disconfirmation.)

Hi, I'm a German student in physics. something i noticed is that in every theory

Hi, I'm a German student in physics. something i noticed is that in every theory we start with a few postulates and conclude predictions about the behaviour of uninlevend objects. Even in quantum- mechanics we can make declarations about things our mind can't even imagine (like electrons). We do all this with math or let's say logic. and here is my question. Why does the universe behave in a logical way? is logic something humans have learned from the universe and only exists in this universe or is logic something that would exist even if this universe wouldn 't exist? Greetings Tobias D. and excuse my bad grammar

There are several questions in what you've asked, all of them interesting. I'm going to single out one of them. If I read you correctly, one thing you're asking is why we can describe the universe using math and logic -- why the universe "fits" our rules of math and logic. We can begin our stab at an answer by noticing that this fact -- that the universe can be described using math and logic -- is weaker than it might seem.

Imagine a computer screen of 1024 by 768 pixels, for a total of 786,432 pixels. For simplicity, imagine that each pixel is simply ether off or on; ignore color. Then there are 2786,432 possible patterns that could show up on the screen. Most of those are a jumble -- not "logical" or orderly in any interesting way. However, each can, in principle, be described. An exhaustive list stating for each pixel whether it's off or on would do. So the fact that the screen can be described using math/logic doesn't really constrain things much at all. Some number of pixels will be on, and the ones that are on will be located at some locations or other. One might say something similar about the universe at large. It could be a real hodge-podge, and yet whatever it's like, that could still be describable using math and principles of logic. (Whether we could come up with the descriptions is another matter.)

I hope that sheds at least some light. However, you might want more. First, we could ask why the universe is describable using relatively tidy math -- elegant laws of physics and such. Second, we could ask why it's describable using math at all, elegant or not. After all, our computer-screen example assumed a lot of order before we got to the details about arrangement of pixels.

On the first question: darned if I know! The universe does seem a lot less messy than it might have been, but whether there's any ultimately satisfying explanation for that fact is pretty unclear, not least because it's unclear what would count as an explanation. We might say, for example, that it's because the universe was designed by a rational deity. Perhaps that's true, but it raises the obvious question why this deity is disposed to make orderly arrangements and why it has an orderly mind. Perhaps the theologians have something to offer here, but I'll admit that I don't. And so one might feel a kind of blank wonder that the universe, God-made or not, isn't a mere mess. Einstein seems to have felt something like this, and I won't quarrel.

This may seem to provide a segue to the second question: why is the universe describable using math and logic at all? The trouble here is that it's not clear what we're asking. The theorems of math and logic seem to be necessary truths, and if so, they apply to any world whatsoever. In particular, they're not up tp us, and they don't depend on the details of this world. No matter what the world was like, nothing would count as having two contradictory properties. If one collection has 2 members and another non-overlapping collection has 3, then the total number of things in the two collections is 5. And so on. We have no idea (or at least I don't) what it would mean for the world not to fit principles of this sort.

Still, one might say that the principles of logic and, especially, math represent abstract forms that needn't be exemplified in the concrete world. Perhaps there's some dim hint of this in the Biblical verse about the world being without form and void before God acted on it. Perhaps it's possible that things could be so chaotic as to resist any coherent description at all. If that's so, however, then we seem doomed not to be able to think about it in any useful way, since it's not clear what it would mean to think coherently in a way that floated free of all logic. However, since this answer itself threatens to disintegrate into incoherence, we've probably reached a good place to stop.

Sometimes people will try to discredit the validity of a scientific experiment

Sometimes people will try to discredit the validity of a scientific experiment by saying that the results don't apply to the real world. Is that a valid argument?

It is a good argument only when there is reason to think that the experimental situation may be different in some relevant ways from the natural situation.

So, for example, tests of nuclear bombs in desert areas or underground yield results that DO apply to the real world.

Tests of drugs in vitro (in the test tube) may not apply in the "real world" of living organisms (in vivo).

Nancy Cartwright is a philosopher of science who has written extensively about these issues.

Does science have its own built in "selection bias" toward things that are

Does science have its own built in "selection bias" toward things that are measurable or relatively more measurable?

Since the Scientific Revolution, scientists have valued the combination of natural science and mathematics. Quantification (measurement) is valued in part because it contributes to precision in making predictions or interventions. The more precise a prediction that is made, the more confirmed a theory is if it the prediction is verified. That said, sometimes the preference for using numbers is valued in itself, or for the aesthetic pleasure it provides some people. And I think you are right to suggest that this may be a "bias" in that it may lead to devaluing sciences that are not, and perhaps cannot be, quantitative.

How reasonable is the way we speak about causality? Say a person catches a cold

How reasonable is the way we speak about causality? Say a person catches a cold. The cause of that cold might be said to be the effect of the cold virus; or it might be said to be the contraction of the cold; or the failure to prevent the contraction of the cold; or the presence of the virus or of the victim wherever it was contracter; or whatever brought either of them to that place; etc. For most things (leaving aside the thorny issue of free will), things that happen are caused by other things. So when we speak of causality, does it make any sense to say that some causes caused whatever we're talking about, and to ignore other, more proximal or more distal causes?

Usually when we ask a question about what caused something, we are engaged in trying to repeat or avoid the same situation, or trying to assign blame and responsibility. So although events have many causes, only a few or one of them may be relevant in a particular context. If I disregard instructions to quarantine myself and infect you with the TB bacillus, then one of the things we might say is that the cause of your getting TB is my irresponsibility. (It would not be helpful to say that the cause of your getting TB was the TB bacillus, or even that the cause was my cough.)

Scientific principles often deal with universal features of existence but a

Scientific principles often deal with universal features of existence but a scientific experiment only deals with particular instances of those laws. So how can scientific laws be deduced purely from experiment? Aren't there always going to be a priori deducible scientific principles?

You are right that scientific laws cannot be deduced from experiment. They can't be deduced a priori (from pure reason) either. Deduction is only one form of inference, however. Usually both induction (generalization) and abduction (inference to the best explanation) are used in science. Induction and abduction are more fallible than deduction. Although scientific theories can be confirmed and disconfirmed, they can't be proven deductively like a theorem in mathematics.

What distinguishes the "social" sciences from the "hard" sciences? Or is there

What distinguishes the "social" sciences from the "hard" sciences? Or is there no such distinction?

There is at least one difference. The hard sciences are capable of predicting what is going to happen before it does. The social sciences have great difficulty explaining why something happened in the way it did even after it happened, and very little success in predicting the future.

I personally believe that humans do not have free will, though I would like to

I personally believe that humans do not have free will, though I would like to hear more arguments against this. My question is, if psychological studies have shown that believing in the absence of free will makes people more aggressive, selfish and antisocial, is it ethical or moral to censure scientific 'evidence' for free will from public knowledge?

This is a great question and one that is becoming increasingly important as neuroscientists and psychologists increasingly suggest that their research is showing that free will is an illusion, a claim I call 'willusionism', and as increasing evidence comes in that shows that these willusionist claims, which the media loves to report and exaggerate, can have (at least short-term) negative effects on people's behavior. I have lots to say on this topic, some of which I say in papers on my website if you want to hear more, but here's a brief take on the issues.

Suppose you believe that free will requires the abilities to make choices based on conscious deliberation and reasoning and to control your actions in light of these choices (against internal desires to do otherwise and without external contraints preventing your action). Free will requires that your conscious self can make a difference in what happens. You may also happen to believe that the only way to have such free will is to have a non-physical mind that is not subject to the laws of nature.

Now, suppose scientists come along and tell you that they have shown that we do not have free will. What will you take that to mean? I think it is likely that you will take it to mean that your conscious self doesn't make a difference in what happens, that you are just a spectator observing the outcome of mechanistic processes beyond your control. And that's the way some willusionist claims are presented. I think it is this response that most likely leads to the 'bad results' of willusionist claims--i.e., the findings that people cheat more, help less, are more aggressive, etc. (studies by Vohs and Schooler and Baumeister and colleagues).

The problem is that the scientific studies have not shown that conscious deliberation and reasoning and self-control are illusory. What they have shown is that there is increasing evidence that we do not need to posit a non-physical mind or soul to explain these cognitive abilities and that, in certain experiments with a specific setup (e.g., Libet's), you can find brain activity that predicts actions before people are consciously aware of their intention to act. But these findings do not show that the brain processes involved in conscious deliberation and decision-making never play a crucial causal role in what we do. It'd be very surprising if the brain processes involved in your conscious planning about what you will do with the rest of your day had no effects on what you end up doing later today.

It turns out that my research on people's beliefs about free will suggests that they are not wedded to a dualist conception of free will (or even one that conflicts with determinism). So, there are (at least) three problems with the way willusionist claims are presented that may account for the bad results. First, the scientists may assume people believe free will requires X when people don't believe that, and they think that their research shows that X is false. And second, when you tell people they lack free will, they will interpret it to mean they lack what they think free will is--i.e., conscious and rational control (Y). And when people believe they lack Y, that likely makes them less likely to engage their capacities to consciously and rationally control their behavior. But third, the scientific evidence has not shown that we lack Y.

There are a lot of issues going on here, and I haven't really explained why we have reason to think humans have some degree of free will even if determinism or naturalism is true (which may be what you wanted to hear). But I hope this helps.