Monday, April 1, 2013

[PHI 3000] Induction as a Time Machine

The original problem of induction, due to Hume, is the problem of justifying inferences from the known or observed (i.e., that with which we have had experience) to the unknown or unobserved (i.e., that with which we have had no experience). For example:
  1. In my experience, all the New Yorkers I've met so far were rude.
  2. Therefore, in general, all New Yorkers are rude. (Or, the next New Yorker I will meet will be rude.)
This argument is not deductively valid. Perhaps all the New Yorkers I've met were rude, for some reason, but there are New Yorkers out there who are not rude. I just haven't met them yet. We could add the following assumption to the argument in order to make it deductively valid:
(UN) What has happened in the past will continue to happen in the future. (Or, past experience is a sure guide for what will happen in cases that we haven't experienced.)
But then what is the justification for (UN)? (UN) can be justified deductively or inductively. However, no deductive argument can prove (UN) true, since (UN) is a contingent, not a necessary, truth. And no inductive argument can support (UN), since such an argument would be circular, assuming the very thing that it aims to support.

Now, the problem of justifying inductive inferences is supposed to hold for all inductive inferences from the known or observed (i.e., that with which we have had experience) to the unknown or unobserved (i.e., that with which we have had no experience). But is there an epistemically relevant difference between inductive inferences from past to future and inductive inference from present to past?

In this NOVA Science Now episode, astronomers draw conclusions about the history of the solar system from meteorites they find on Earth in the present and evolutionary biologists draw conclusions about the evolutionary history of our species from lice they find in our hair in the present.



Watch Where Did We Come From? on PBS. See more from NOVA scienceNOW.

Should we have more rational confidence in these inductive inference from present evidence (e.g., meteorites and lice) to past (e.g., evolutionary history of the solar system and our species)?



Watch Where Did We Come From? on PBS. See more from NOVA scienceNOW.

Perhaps. Consider that the past is supposed to be closed, insofar as what has happened has already happened, whereas the future is supposed to be open, insofar as what will happen hasn't already happened. If so, then when we reason inductively from past to future, rather than from present to past, there is simply more that we can get wrong.



Watch Where Did We Come From? on PBS. See more from NOVA scienceNOW.

If this is correct, then does that mean that we are more likely to get our present-past inductive inferences right than our past-future inductive inferences simply because there is a lot more we can get wrong about the future? And if so, should we have more rational confidence in present-past inductive inference than in past-future inductive inferences?

11 comments:

  1. I believe that we should have more confidence in making future inductive inferences. For example I can infer that if it snows than it will be cold outside. This is based on my past experience of it being cold outside when it snows. The reason I have more confidence in this kind of inference is that when it does snow I will be able to verify my prediction and adjust my belief accordingly. But while inferring about the past it is much harder to strengthen an inductive inference since there is no way to go back into the past to verify the inference made. The only way to strengthen and inference of the past is to find new evidence to strengthen a claim or to notice support that was overlooked the first time around. Despite the future being open and the past being set in stone (closed), the future can be actively observed and tested.

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    1. Thanks for your comment, Nil. I am not sure I see how “being able to verify our predictions” should make us have more rational confidence in past-future inductive inferences than in present-past inductive inferences. Could you say more about that?

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    2. The reason for this is that the initial prediction for both the present and the future are equally strong or you can even argue that the past is stronger, but with the future we can observe the results of that prediction and we can keep observing occurrences in which our prediction for the future comes true, for example using cloud patterns to predict the weather. By observing results we can make stronger cases for each future prediction, but when we deal with the past there is no way to strengthen the prediction no way to know if it's true. At least in regards to the future we can rest assured that we can have confidence that we will see whether we were wrong or right. I personally compare this to calling a bet in a poker game. Sometimes a player will make a bet just to see the other players hand so as too make use of this information in the future, in both cases the player comes out with something useful a bigger chip pool or knowledge. Thus I believe that we should have more confidence in making predictions of the future because we gain knowledge in the case of the prediction being wrong and in it being right.

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  2. I think that this means that we are more likely to get our present- past inductive inferences right than our past-future ones. For example, as shown in the video, people work very hard to piece together the past of our solar system; from how it came to be to when it began. The present allows us to have evidence of the past and of what went on, although it's not "complete" evidence. The meteorites serve as such evidence as they allow us to see that a supernova event must have definitely occurred at the time of the solar system's creation. What the supernova event actually did or consisted of still remains a mystery, but it brings us one step closer to what we want to know. Although past-future arguments have evidence as well, such as the sun will rise tomorrow since it has risen everyday so far, the evidence isn't as definite. We see the sun rising every morning because of the earths own rotation and its rotation around the sun. What if tomorrow, for some odd reason, the earth stops rotating about the sun? Although that's not highly likely, it is still a possibility. We do not know what will happen in the future because we have not seen it yet, making the "evidence" less reliable. Evidence for present-past arguments are more definite and reliable than evidence for past-future arguments.

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  3. I believe that it is more likely to get the present-past inductive inferences right rather than the past-future inferences. When we say present-past, we say that the inferences we make now about the past are the ones that are better able to make sense. Why is that? Well, I think that because we have concrete evidence of what has already happened, we can build upon ideas that we make now. Through different hypotheses and different tests that are currently available, we can trace some things to the past. For example, the meteorites that we find today can be traced back to the past using different techniques that have only recently been available. In the past, this technology was not even invented for us to make any conclusions about any single meteorite. Or even with the lice example. By knowing that certain lice live within clothing, we are able to trace back to the times when humans wore clothing. There are so many things that we find today that can be traced back to the past which allows us to make the inferences we make that are present-past to be right. If we were to make inferences about the past-future, sure some of the things we assume may be right, but they will never be concluded to be right unless the event has happened. Therefore, we should definitely have more confidence in the present-past inductive inferences than the past-future inferences.

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  4. I think we should have more rational confidence in present-past inferences over past-future inferences. Some scientists dedicate their lives to studying the events of the past to better understand how things were started and created. Although it is impossible to go back and find out first hand what occurred, the inferences that are made by scientifically discovered evidence would give me greater confidence than any inferences made for past-future arguments. I feel like the thing about the future is that anything can happen. Our society believes in this idea and it can also be a main focus on how people interact and make decisions in their respective lives. Although one can make an inference about what will happen tomorrow based on what has happened in the past, it doesn't mean that it will necessarily come true because the world around us is always changing and not much stays the same over time. That is why I would have more rational confidence in present-past inferences over past-future inferences.

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  5. Christina S - PHI 3000April 9, 2013 at 10:06 AM

    How can one know that social mobility is more likely not to happen at the rate in which is popularly stated, especially by the hopes of the America dream: Statistical evidence and methodological procedures. Although we cannot be absolutely sure on anything, sociological inquiries serve as a scientific research of people past/present/future and can identify trends, along with possible threats to any assertions gained through research. Perhaps I am biased, but I believe that through the research of the past, ideas about the future can be formed and could be justified (as long as the qualitative and quantitative evidence backs it up).
    In this reasoning, I believe that any inductive reference, whether it is present-past or past-future are intimately tied together and one isn't more rational than the other; however, past-future inferences seem to be more justified. Unless there is history documented, which could be skewed by bias or in the realm of hard science, accident, one cannot know that one's assertions are correct about the past from the present. When the scientist asserts that we are more likely to have been created by supernova fall-out, one argument could be perhaps this didn't happen and there is another particle we are unaware of that produced similar properties noted in the film. We would never truly know, but through research, more justification can be found through past-future research (like sociology).

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  6. I agree with you Dr. Mizrahi, we have a much better chance to get our present-past inductive inferences correct in comparison with our past-future inferences. As you stated, the past has already happened, giving us definite events. These definite events give us something solid, something that can be proven. Using present clues can help decode the past. The video on this page shows the evidence of meteorites that could provide an explanation of the universe’s creation. The video also cites looking into lice to figure out human evolution. On a more ordinary level, we use evidence like this to solve crimes. Practices of DNA testing and the entire science of forensics helps figure out paternity and where a shooter stood when discharging his/her gun. Using current evidence to figure out a past event is commonplace and widely accepted, for good reason. Using the present to figure out the past is simply trying to make something that already happened clearer. In the meantime, past-future inferences use the past to prophesize the future. While there are nearly certain examples of this type of inference, namely the rising of the sun and the waste of buying a lottery ticket, there are many other much more hazy examples. There are statistics in sports such as, “The Yankees are 13-0 when leading by more than three runs at the end of the 8th inning.” A memorable one from a few years ago was that Tiger Woods was undefeated whenever he held the lead going into the last round of golf. In the last four years, he has blown two of these leads. Using the past to postulate the future in these cases, and many more cases, was wholly incorrect.

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  7. I believe that it is more likely for us to get inferences about the past correct than inferences about the future that are based on those same past experiences. This increased likelihood of getting future inferences wrong stems from the nature of the experiences which we use to reach the future inferences. In order to make inferences about the future, we will need our experiences from the present as well as inferences about the past. These inferences about the past can be based on many pieces of evidence, such as the chemical composition of meteorites or the evolutionary patterns of lice, but the main flaw with these inferences is that there is no way for us to be conclusively certain they are true and therefore there is a chance that they are wrong. Now if these possibly wrong inferences about the past are then used to extrapolate into what might happen in the future, there is an even greater chance that this future inference is wrong simply because it was already based on an incorrect earlier assumption. As a result of this, I think we should have more confidence in present-past inferences than past-future inferences because the compounding of inaccuracies as well as the “openness” of the future causes past-future inferences to be less reliable.

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  8. I believe that we are more likely to get our present-past inductions correct than out past-future inductions. The past is behind us, what has happened has happened, it cannot be changed or altered in any way. This is unlike the future which can change at any moment because of minuscule daily occurrences. With the advanced technology we have today we are able to make inductions of the past bases of off scientific evidence. Besides the examples of the meteorite and the lice that we looked at in class, another example of how technology lets us make inductions about the past is through Carbon-14 dating of fossilized dinosaur bones. Through this method we are able to make inductions about when we believe dinosaurs lived and died out. These methods can be used to make inductions about the past because the past will not change. There is no way we can use any method to predict events of the future, which is always changing. For example, if the past week has been hot, I cannot make the assumption that tomorrow will be hot as well because there could be a sudden cold front that moves in. Because we can use evidence from today to figure out events of the past and not events of the future, present-past inductions are more reliable than past-future inductions.

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  9. I believe that both past-present and present-future should have equal weight on them. Clearly, they both have one thing in common: the present. Since both inferences rely in what we have right now in the present, we cannot say one is more right than the other. Both inferences stem from the same supporting evidence. Say you have a pillar, it represents the present. You can build the past on this pillar, as well as you can build the future on this pillar. Is it logical to say that the pillar that holds the future is weaker than the pillar than holds the past? No, of course not. Inferences about the present-past are equally as wrong as the inferences of the present-future. No one can go back in time and validate the speculation we have made about the past, as well as no one can go into the future and validate the speculation that we have made about the future. However, there is one small difference, the real difference: we are moving forward into the future. It lets us see that our predictions unfold into reality or see them become wrong. We can’t roll backwards and see the past. That is why we are fooled into believing that we can be wrong about the future and that the past is more trustable, the fact the we find out we're wrong or right. But in fact, both are reasonable probabilities, just that we can verify one and not the other. But doesn't mean we can have more confidence in the latter.

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