Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Scientific Experiments

  1. Dec 3, 2009 #1
    I thought this was the appropriate place for what is essentially (at least to my mind) a pholosphical idea.

    Has there been a fundamental change in the way scientific experiments are evaluated?

    Has the standard of proof shifted, as indeed it probably has to, due to the phenomena we are investigating?

    I was taught at school that the scientific process was to investigate, to evaluate, to form a theory and to test that theory. In particular that one must conclude that every part of a theory happened as envisaged and could have no other possible cause.

    But as the scope of scientific theory continues to grow we focus on the extremes: the 'infinitely' small, sub-atomic particles; the 'infinitely' large, cosmological entities and processes; the 'infinitely' brief, etc, etc.
    We seem to be tending towards the line of argument; if A then B and if evidence is found, that can be cosidered to comply with A, then B is considered to be proven.

    Please understand that I am not in any way decrying modern science, for perhaps this has always been the way?

    The example of Phlogiston comes to mind: first given that name by Georg Ernst Stahl, in 1703 and said by some to have had negative weight, the theory lasted for nearly 100 years.

    Last edited: Dec 3, 2009
  2. jcsd
  3. Dec 3, 2009 #2
    Good question! You're definitely talking about philosophy here, or more specifically, philosophy of science. Philosophy of science asks questions like "what does science tell us?" and "what are the limits of science?"

    Many people have spent their lives trying to answer these questions, and we still don't have consensus. The short answer is, however, is that you have been lied to :smile:. You'll find that this happens a lot actually, so it's good to ask what's really going on. The fact is that we don't really know as much as we say we do about a lot of topics, but in order to teach anything without getting bogged down we just have to pretend that some things are true when they are deemed close enough.

    Science works on the principle of induction. We assume that if we take a measurement repeatedly we will always get the same reading. We assume that the same principles of nature that cause us to measure Earth's gravity to be 9.8m/s^2 at some locations will hold at all locations. We then further generalize and predict what the acceleration due to gravity will be on planets we have never been to. The problem with induction is that we can never have absolute proof that things will always hold up how we think they will. This is known as http://plato.stanford.edu/entries/induction-problem/" [Broken].

    Furthermore, we can always come up with multiple alternative theories that fit experiments equally well. There are always other possible choices. Are you familiar with Galileo and the copernican vs ptolemaic models of the solar system? Both the heliocentric and geocentric models fit experiments equally well. We ended up switching to thinking of the sun as the center of the solar system, rather than calling earth the center of the universe, purely because the math is more simple when we put the sun at the center.

    In philosophy there is a famous thought experiment about "grue." Grue is a property of objects which causes them to be green before some year t and blue afterward. Many of the objects you had theorized were green might actually instead be grue. You have equal experimental evidence for both the theories of green and grue. From http://en.wikipedia.org/wiki/The_New_Problem_of_Induction" [Broken]:
    You ask another question about having only indirect experimental evidence to support our theories. This too has always been the case, although is is more clearly evident in modern science. When you use an electron telescope to "see" something, you are relying on all of our theories involving how that technology will work. When you just step on a scale you are relying on our theories of gravity to present you with a proper measurement of mass. The form of argument you gave though, if A then B and A is true so B is true, is perfectly valid. If, in fact, you have proven A, then you have proven B without a doubt. The problem is, as discussed above, you can't ever deductively prove any scientific theories (although you can prove them wrong).
    Last edited by a moderator: May 4, 2017
  4. Dec 3, 2009 #3


    User Avatar
    Gold Member

    This is a very interesting question. And we could talk about both the theory and the practice.

    The theory of how to do science is still pretty much what it always was. Though the limits are better appreciated perhaps.

    Science is modelling. It is a mistake to think it is purely a search for "the truth". It is about creating general models which generally predict the world - or more accurately, predicts the kinds of things we are most interested in predicting. So modelling is tied to human purposes. And the main purpose (that gets socially rewarded) is the making of machines. Technology. Control over the world.

    This would then be one kind of change perhaps - that theory building has become even more closely tied to the technological fruits that may result.

    There is also the status research, the national prestige research - men on the moon, supercolliders, etc. This is science tied to political purposes - though there is good spin-off for military and economic purposes when it comes to nuclear physics, space races, etc.

    Well, already I'm talking about the practical changes. But then there is a whole other kind of change in the fact that there are vastly more academics doing "research" at universities. And that so much of the straightforward science has been done. You know have a situation where multiple standards of quality apply. So there are domains of high rigour and others where anything goes. It is just a much more varied eco-scape these days. It is hard to speak of "science" as a monolithic or homogenic discipline and judge it good or bad.

    Returning to your key point, which seems to be about the difficulty of making the measurements that confirm the theories, yes, at the extremes we are getting towards the situation where we can essentially make only the one measurement. The state of the universe we are within.

    And people also dream they may discover a ToE - which I see as a measurement-less theory of reality. Just from considerations of pure symmetry, there may be reasons why we live in this 3D realm with certain particle symmetries, etc. A few constants might be randomly chosen as the way this symmetry breaks.

    Would this still be science? Well it would probably not deliver us much in the way of new technology. It would probably not be testable by new kinds of measurement (though it would have to fit all the existing ones).

    But it could be more like science as the pursuit of pure truth. Indeed, more like philosophy!

    And personally I don't see that as a bad thing. I would spare a few taxpayer dollars to fund it.

    And with the wrangles over the status of string theory and anthropic principles, we can see people trying to thrash out the rules for entering this next phase perhaps.
  5. Dec 3, 2009 #4
    This actually touches on a pretty major disagreement in the philosophy of science. Which comes first, evidence or hypothesis? Its a problem with formulating the method.

    This is related to the rationalism vs empiricism argument, as it deals with what inspires a theory. Some theories do indeed seem to come from our imagination... and then get proved or disproved via evidence. But at the other end of things, sometimes scientists are inspired by the evidence, that is, the evidence points to the theory that no one thought of before.

    Its really a chicken and egg problem. Scientists are always evaluating evidence, but they can also be inspired by seemingly unrelated things.

    The use of 'double blind' experiment also comes to mind as a 'development' in how science is done.
  6. Dec 3, 2009 #5
    Oh, so is psychology a science now :wink:? I think that's the development.
  7. Dec 4, 2009 #6


    User Avatar
    Gold Member

    Ah, well at least that is always an easy loop to get out of.

    Understanding begins in a vague state of development and becomes crisply developed - dichotomised into generals and particulars, models and measurements. The two naturally go hand in hand as in synergistic activity, each driving the other in their opposed directions. So no need to worry about which comes first.
  8. Dec 5, 2009 #7
    Both are, but psychology is just a new field of study, its not a change in method. You can apply 'scientific method' to anything really, including economics, and even astrology.

    Double blind is a good example of how to control for bias, and the importance of the impact of the observer, has been something that has come slowly to science. Even now, physicists are grappling with this in terms of quantum theory.
  9. Dec 5, 2009 #8
    That doesn't really address the problem of defining method.
  10. Dec 6, 2009 #9


    User Avatar
    Gold Member

    This is the method....

    Understanding begins in a vague state of development and becomes crisply developed - dichotomised into generals and particulars, models and measurements. The two naturally go hand in hand as in synergistic activity, each driving the other in their opposed directions.
  11. Dec 6, 2009 #10
    No there has not been a fundamental change in the way we do science. While yes I do agree one is needed.
  12. Dec 6, 2009 #11
    Thank you Gentlemen, (No, I must not assume that, must I?), [STRIKE]Gentlemen[/STRIKE]: Good People, one and all, it is a much broader subject than I had anticipated, and deeper too.

    In my original post I expressed the following opinion:
    To which I received the following reply:
    (thank you, kote, and thank you too for a good summary of the difficulties, your reference to the fascinating problem of induction was very welcome:smile:.

    But I had mixed up my own line of reasoning there; what I should have said was: We seem to be tending towards the line of argument; if A then B and if evidence is found, that can be considered to comply with B, then A is considered to be proven.

    An example of this would be: 'if a star has planets, and if their orbit is in our plane, then that star's brilliance will diminish regularly. Then if such regular dimming of the star occurs, the star has planets'.
    (please understand that I am not saying that this is what scientists have said, but it is the way it has been reported) and my question would be "but is there anything else that could give rise to the same evidence/observation?"

  13. Dec 6, 2009 #12
    Interpretations of what a physical finding means, will always be contested. If A then B, and if B then A will hold for as long as we find a contradiction. When we find one, our assumptions on which a scientific investigation is always based, will have to be revised. You can say that this is what is currently going in physics.
  14. Dec 6, 2009 #13
    That is your opinion. There is a wide array of opinions within the philosophy of science on this particular topic, and there has been a distinct shift in opinion over the last several centuries.

    And really, you haven't said much of anything about an actual method. If anything, what you have said indicates a lack of discernable method.

    One of the problems with defining any method is that scientists often find the greatest success by being unorthodox... while others work with the tools that function best in their field, which means there are either many different methods, or none at all, that is, anything that generates success... wins.
  15. Dec 6, 2009 #14

    I agree with this. I have to look up who said something to the effect of:

    The greatest barrier to new knowledge in science is its past success.
    Last edited: Dec 6, 2009
  16. Dec 6, 2009 #15


    User Avatar
    Science Advisor

    Apeiron, what do you mean by "crispness"?
  17. Dec 6, 2009 #16


    User Avatar
    Gold Member

    I use it specifically as the complementary term to vagueness, so it is a technical term.

    It would mean definitely and clearly existing, or fully developed, present in most certain form.

    The point is that most people assume that all reality IS crisp. Something either exists or it doesn't. So crisp would be a redundant term because that is simply the way things are. Any vagueness would be semantic - as in the sorites paradox.

    But I am interested in logics founded on vagueness - the dichotomous separation of pure potential. So the logic of Anaximander, some versions of Tao, and of CS Peirce. Vague and crisp are two ordinary english terms that seem to come closest to capture the essence of the technical ideas involved.

    I picked them both up from Stan Salthe who uses them in hierarchy theory approach.
  18. Dec 6, 2009 #17


    User Avatar
    Gold Member

    It is an opinion supported by argument and shared by others. I've cited Rosen's modelling relations and anticipatory systems work here often enough.

    Your problem is that you have not once either shown the basic idea of dichotomisation is in error, or provided some arguments and references in support of some other view.

    I can only conclude you don't actually study current epistemology and are only responding from a casual layman's understanding of the issues.

    So here are three refs for you to chew on.

    The first compares Popper and Rosen. The second is a general intro to Rosen. The third is about bottom-up~top-down, vague to crisp, dynamic logic, based on Grossberg's anticipatory neural nets.



  19. Dec 10, 2009 #18
    No, my problem is you repeat this stock answer about crispiness and dichotomies in response to just about any issue that comes along, and ignore any references that disagree with your rather narrow understandings. I know what a dichotomy is, I also know what a false dichotomy is.

    That crisp enough for you?
    Last edited: Dec 10, 2009
  20. Dec 10, 2009 #19


    User Avatar
    Gold Member

    No. Please tell me what you understand by the terms?

    I am still waiting for even the vaguest argument against the foundational importance of dichotomies in philosophical thought.

    I have argued that they are the ONLY method by which people have arrived at fundamental concepts. I have not found a counter-example.

    So a crisp response on that particular question would be much appreciated.
  21. Dec 11, 2009 #20
    Ok, for one thing I never said 'dichotomization is an error'. You seem to be going out of your way to misrepresent me.... once again.

    What I said was that dichotomies are not fundamental to epistemology. Dichotomies are binary constructs, which describes two distinct 'defined' states.
    As in: 1,0
    As in: A and not-A

    Binaries can be *useful* in describing things, but knowledge is not limited to them.
    A binary is just a framework.
    We can describe, for instance, something with 3 states, a trichotomy.
    Past, Present, Future
    Dead cat,alive cat,deadandalive cat
    Wave, particle, wave-particle.
    Human color vision cones: short (blue), medium(green) and long (yellow-red)

    The strength and weakness of dichotomies (and trichotomies) are that they are abstractly defined, or limited by definition. We can map a dichotomy onto anything, and that can be useful, but it can also be misleading, and invariably is, at least on some level.

    Red and Blue for instance could be used to describe light. Its either red or not-red(blue). (ie green would be included in blue and yellow included in red)
    But given what we know about the biology of the human eye, saying something is 'either blue or not blue', while it may be technically true, it doesn't accurately describe what you are talking about. Its misleading, because you have mapped a dichotomy onto something that is better described in another way. In fact, color is just one aspect of light the eye can see.

    We can also describe something as a spectrum, or as 'approaching a state'.
    A dichotomy is simply a type of map, or a convenient way of organizing. Its not fundamental to knowledge. And there are other systems of knowledge, as I pointed out before, which deal with unities, or wholes. The fact you are not impressed by them is irrelevant.

    But I'm just a poor casual layman after all, you're much more impressive with your overly verbose, meandering, sermons about crispiness.
  22. Dec 11, 2009 #21


    User Avatar
    Gold Member

    If dichotomies were merely useful for counting things, then they would indeed be trivial - mere numerology.

    There are many examples of this like the five chinese elements, or the 12 astrological signs.

    Trichotomies are actually hierarchies when they are "good" - conceptually fundamental. And hierarchies of course are formed by dichotomies. When what has separate then mixes.

    So have you identified any legitimate triads here?

    Past, Present, Future - This one is tricky as it depends how you view time. It deserves a thread of its own.

    Dead cat,alive cat,deadandalive cat/Wave, particle, wave-particle - particle~wave is a dichotomy and their superposition state would be the vagueness from which they arise as seperate alternatives. So really just a dichotomy. Schrodinger's cat I suppose is a dichotomy in that we can divide the world into bios and a-bios. But it is not a fundamental distinction about nature.

    Human color vision cones - you will be aware how the eye actually works? That dichotomies apply widely? As with the "on-center" and "off-center" ganglion cells. And the colour opponent channels. So perhaps three cones, but four primaries - the colour pairs of red~green and blue~yellow. Even colours don't compute unless there is A and not-A.

    Not blue would be yellow. Not red would be green.

    But while it is revealing that the brain relies deeply on dichotomies (attention~habit, ideas~impressions, what~where, sensory~motor) this is not quite the same as the philosophically fundamental dichotomies like substance~form or stasis~flux.

    Taking stasis~flux for example, can you think of a third or even fourth possibility here? Stasis and flux, by being mutually exclusive, also exclude all other options.

    Well you might suggest that a third thing is the superposition of stasis~flux - and I would agree that this would be a vaguer undivided state.

    Or you could also say that a mixture of stasis and flux is the third thing - and I would agree that this is then the triad of a hierarchy. We can imagine such a mixture being fractal. Indeed, as the NK Boolean networks of Kauffman where the fluid and the crystalline regimes are mixed "to the edge of chaos" as they used to say.

    This is an assertion not an argument.

    Again, as Bohr, Hegel, Peirce and many others have pointed out, when alternatives become mutually exclusive, they must be fundamental. It is not a convenience that the discrete and the continuous exhaust the possibilities. If you can show it is actually just a convenience, then you will have an argument.

    Again, focus on what seem to be the fundamental dichotomies that have arisen in the history of philosophy and thought generally.











  23. Dec 11, 2009 #22


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    From my perspective at reading this thread, I see no specific discussion on experiments, as indicated in the topic. It appears more to be a generic discussion on the workings of science, rather than the role of experiments. I also wonder how many people who offered responses in this aspect has actually done any extensive scientific experiments. This isn't a criticism. It is merely something I often use to judge the background expertise of the contributor.

    It is highly premature to make any kind of conclusion or judgment if you are not fully aware of how things are done. Using generic impression, or based on things you have no first-hand knowledge of, will simply perpetuate misconception, misinformation, or downright false impression. The "standard" impression of how science works that has been mentioned here is grossly outdated. I can cite many new physics, for example, that came out of nowhere other than simply an expected experimental observation that no existing theory at that time had predicted (example: CP-violation, superconductivity, fractional quantum hall effect, etc... ). In other words, the experimental discovery caused the impetus for a new theory that expanded physics. In fact, if you've read Harry Lipkin's sharp article "http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHTOAD000053000007000015000001&idtype=cvips&prog=normal" [Broken]", you would have come out with a strong impression that it is experiments that drive physics.

    The process of knowledge doesn't follow one single path, and it would be quite naive to think that one can easily make clean summarization of how things are done in science. Not only is there a closed loop, but it is also a self-consistent feedback loop, where at each stage, both theory and experiments feed off each other to refine the understanding of something. This is especially true when the search for a valid description of a phenomena is still ongoing (example: understanding high-Tc superconductors). Each experimental discovery drives a refinement of existing theory, or even a formation of new theory, which then drives more experiments that tries to test those theories, while in the process, often makes startling new observations (example: the pseudogap in the underdoped phase), which in turn, goes back to the theorists to figure something out. And the circle continues.

    What philosophical principle that you derive out of this is your expertise, not mine. But it would help if you first have the accurate "data" to work with, rather than some handwaving impression. And for background info, I am an experimental physicist.

    Last edited by a moderator: May 4, 2017
  24. Dec 11, 2009 #23
    Hi ZapperZ. Which standard impression are you referring to? There is a difference between what contemporary scientists do and the general concepts of inductive empirical inquiry. There are also different philosophies regarding each.

    Every one of us does experiments every day in the sense of pure empiricism. I believe that the sun will rise in the morning because I've seen it rise every morning. Every time I wake up is a new experiment in a sense. When we talk about this kind of experiment, we certainly aren't saying anything about the sociology of contemporary physics, or paradigms, or how science is or should be done. We are talking about the philosophical underpinnings that allow us to have science at all and the limits that those underpinnings place on the knowledge science can give us. These basics are necessary for us to consider how valid or not it is for experiments to drive science, or for theories to drive science, etc.
  25. Dec 11, 2009 #24


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    The topic asked about "scientific experiments". I used the conventional understanding on what is implied by that, rather than anecdotal observations or simply observations without any kind of systematic analysis of both the observed and the observer. It would be an insult, don't you think, to think that your everyday observation is anywhere identical to a typical scientific experiment at, say, the LHC, and putting those on the same ground.

  26. Dec 11, 2009 #25
    I don't think it's an insult at all. Logically the two use the same methods to draw conclusions about the correlation between observations. It's easier to consider the logic using simple examples than it is to start off with a very complicated experiment that took thousands of years to arrive at. Empirical knowledge is gained through the inductive consideration of observations and the development of theories to model those observations. If I did not perform a systematic analysis on my observation of the sun rising each morning, I would never come to expect that it will rise regularly.

    I'm not disagreeing with you at all about contemporary science. Anyone who has taken an introductory philosophy of science course will be familiar with your concept of experiments leading to new theory. Kuhn's The Structure of Scientific Revolutions is standard reading, as are Popper and Feyerabend. Kuhn draws a distinction between "normal" and "revolutionary" science, placing the creation of new theories arising from unexpected and unexplainable observations in the revolutionary category. Feyerabend's Against Method argues that there is no such thing as a strict method that science follows (or can or should follow).

    If anyone reading has been thinking that, beyond the basic inductive method of inference from repeated observation, there is a particular structured "scientific method" that is followed, I recommend taking a look at http://en.wikipedia.org/wiki/Epistemological_anarchism.

    The Stanford Encyclopedia of Philosophy also has good introductory articles on http://plato.stanford.edu/entries/thomas-kuhn/" [Broken], and other related topics (see "Related Entries" at the bottom of each page).
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook