If you have any interest in reasoning correctly but have never taken the time to learn Bayes’ theorem, you should delay no longer as Bayes’ theorem is the correct way to update your beliefs based on the evidence gathered. I use this reasoning very frequently and only haven’t attempted to explain it here because it is math and jargon heavy. To get around this issue let’s first try a visual example and later see what the generalities are which make up the most important equation you’ll ever learn.
Say I have two jars each containing 100 marbles. One has a 50/50 split of red and green marbles and the other has 90 red marbles and 10 green marbles. Now suppose we were going to blindly draw marbles out of one of the jars without knowing which jar we are drawing from. If we draw a green marble on the first try my intuition tells me that it is much more likely to be that we are drawing from the even jar than the majority red jar because there are five times as many green marbles in the even jar. In my experience this makes sense to most people but why is this the case? Well this is where the math comes in.
To answer this the question is we must know what is the probability of my hypothesis (H) given my observations (O) which is P(H|O). According to Bayes’ theorem P(H|O) is equal to: P(O|H) P(H) / P(O).
For those weary of math this can look intimidating but P(O|H) is just the probability of seeing the observations (O) given the hypothesis (H), in other words the degree that H predicts O. And P(H) is just the probability of the hypothesis (H) before the observations (O) are taken into account. All of that is then divided by P(O) which is the probability of seeing those observations (O) irrespective of any particular hypothesis. This giant equation really breaks down to how much a hypothesis is inferred by an observation which is, intuitively, proportional to the amount that hypothesis predicts the observation while accounting for how likely you are to see the observation under any circumstance and how likely you already consider the hypothesis to be. This is the technical explanation for why if you draw one green marble it’s likely you’ve drawn from the even jar and if on the second try you draw another green marble you become even more confident that you are not pulling from the majority red jar.
Confused? I hope not, but admittedly this is one of the few areas where I find myself unable to recall what all that jargon looked like to me before I grasped the concepts. For those new to Bayes’ theorem I think seeing the concepts with Venn diagrams and Eliezer Yudkowsky’s (lengthy) intuitive explanation are the most useful but I find the best way to learn this idea is to apply it with visual or familiar examples. In upcoming posts, I’ll be doing both.
For as long as there has been philosophy there have been arguments about whether everything was ultimately physical or whether human minds may be an exception to this rule. In the time of Plato or even Descartes this could have been a reasonable debate but we don’t live in that age anymore. Since then we have put these ideas to the test. Every time we have found the brain to play a role for some aspect of mental life, whether that be in sensory experience or memory, we have gained reason to believe minds are physical.
Indeed there have been thousands (if not millions) of independent data points and every one of them has fit the physical mind model and every new fact that fits this model is not only makes physicalism more likely it makes the theory that minds have some nonphysical competent less likely. Sure there are things we still don’t understand about the brain and of course one could now argue that the kind of dualism is true just happens to be the variety in which only some portion of the subset of mental life we haven’t yet correlated with the brain is due to the soul. The question is that rational to do? Rational or not, many dualist philosophers have done just that arguing, for example, that they can imagine a “philosophical zombie” who has all the physical and behavioral traits of a human but is not conscious. Whether or not you can imagine such a creature, it should make essentially no difference to our conclusion. That is unless you are to claim that such possibility of imagination is the millions-to-one argument in favor of dualism which would be needed to rescue it from being extremely unlikely.
As Dan Dennett rightly pointed out who would be persuaded in the least by someone who claimed they could imagine a dog with all of it’s biological components functioning but which wasn’t really alive? No one would believe that was a good reason to accept vitalism, the belief in a mysterious life force, and similarly we should dismiss claims of being able to imagine a person with a fully functioning brain but not conscious as equally pitiful. In the face of the overwhelming evidence that has come in exclusively on the side of physical minds we’ve long surpassed the point where belief in dualism is reasonable. In fact this rule applies not just to dualism but beliefs in chakras, qi and a host of other pseudoscientific ideas which still subsist in alternative medicine but which science based medicine has rightfully abandoned.
This is one reason why though I’ve recently addressed several arguments for dualism, the era in which there was still a debate to be had has long since gone. Even if you believe dualism is coherent, which as I’ll explain in the second part of this look at dualism that you shouldn’t, we must consider dualism very unlikely just by considering the evidence neuroscience has gathered over the past few centuries.
There are several tricks to accomplishing your goals, becoming more rational and communicating skepticism more effectively, here are a few that have caught my attention of late.
*Richard Alley’s new series How to Talk to an Ostrich is an almost perfect example of communicating climate change to those who don’t accept it (the name is the only issue).
*Julia Galef over at Rationally Speaking has a great look at the use of thought experiments in probing your reactions and motivations.
*Beeminder and Stickk offer services that let you bet against yourself, including that money potentially going to charities you despise, in order to accomplish your goals.
*Similarly Prediction Book allows you to wager on your predictive ability with the goal of making you more realistic about your predictive ability in different fields
I have the intention of using several of these tools in the near future. Hopefully I’ll be able to share some success stories soon as well.
Imagine someone presents you the following argument:
On a straightforward reading that conclusion seems harmless. You probably understand car propulsion has something to do with engines and fuel so concluding Geller’s car has some force is no stretch. Now what if I told you the person making this argument was arguing that Geller’s car was not enabled by the typical internal combustion engines you vaguely grasp and indeed not by any understood process at all. Instead they claim Geller’s car is moved by telekinesis and that this argument demonstrates that fact. You see telekinesis is “some force” that could in theory enable a car to drive.
Now ignoring for the sake of argument that we could actually test this claim, what’s wrong with this argument? The contention is clearly over the term “some force” as what leads you to accept the first premise is that there is abundant evidence of cars running because of physical causes. In fact all of the evidence for working cars is tied to fuel, engines, gas pedals, etc. and there is no evidence at all that cars can function due to telekinesis or that telekinesis of any kind is possible. This clearly is a case of using a term that has multiple possible meanings and switching between those two meanings, a classic fallacy of equivocation.
This scenario is strongly analogous to the Kalam cosmological argument which argues that the universe was created out of nothing and goes:
Where the Geller telekinesis argument equivocates between known physical forces and telekinesis for usable cars, Kalam equivocates between creation out of something (meaning a rearrangement of physical materials), and creation out of nothing (literally meaning something coming from nothing), in the use of “begin to exist.” In both cases all of the evidence for the acceptance of the first premise is in one meaning of a term which is then abandoned the rest of the argument. We have plenty of reason to believe things “begin to exist” if you mean the rearrangement of preexisting materials. However just as we have no evidence for telekinesis we have no evidence that things begin to exist out of nothing and yet this is what the proponents are arguing for. Ultimately simply because you can bundle two different meanings under the same label doesn’t mean we must accept one meaning which has no evidence supporting it.
I’ve previously addressed Kalam at length but I think this is a handy way to see one major issue with the argument that most people can understand.
I think I agree with creationists. No not about the existence of The Real Housewives of Bedrock but about the implications of evolution should have for theism in general and the Biblical religions in particular. Creationist outfits have been telling anyone who would listen that accepting evolution is incompatible with belief in god generally and the Bible in particular and for once I think they are right but naturally for reasons very different from what they’ve been suggesting. Unlike them I readily acknowledge there are lots of Christians and theists in general who accept evolution but the relevant question is are the beliefs really compatible?
The common claim of those who accept theistic evolution that evolution could have been a guided process just isn’t good inference. Modern evolutionary theory places enormous limitations on the history of life on this planet essentially all of which didn’t have to be true. The most common example is the claim that all life has common descent as all life didn’t have to be related but observation and experiment have overwhelmingly confirmed this. Even descent itself didn’t have to be true as a designer isn’t limited to breeding to produce new organisms. A designer just isn’t bound to a “branching tree a life” and could create organisms which have nothing or very little to do with previous organisms which means there were infinite paths to the current set of species.
The argument from intentionality (AFI) relies on the claim that one physical state can’t be “about” another. That is to say intentionality, the property of mental phenomena directed upon some object, can’t reduce to physical states of the brain and because minds clearly have this capability then dualism must be true. Most simply A can’t be “about” B if they are both purely physical. Many dualists argue this is because intentionality is fundamentally irreducible and to reduce it would be to explain something else. They claim any attempt to reduce intentionality to something nonmental will always fail because it leaves out intentionality. As philosopher John Searle argues:
Suppose for example that you had a perfect causal account of the belief that water is wet. This account is given by stating the set of causal relations in which a system stands to water and to wetness and these relations are entirely specified without any mental component. The problem is obvious: a system could have all those relations and still not believe that water is wet… You cannot reduce intentional content (or pains, or “qualia”) to something else, because if you did they would be something else, and it is not something else. - The Rediscovery of Mind p. 51
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As a skeptic I’ve read and taken part in many debates with believers who follow the familiar pattern: A debate on a topic begins and after some time the believer acknowledges that the skeptic has made some strong arguments but instead of acknowledging that maybe they should reconsider their position the believer says “you just have to have faith.”
Now we all know you can’t argue with faith because it is by definition impervious to evidence but you can point out that the acceptance of faith isn’t a good thing epistemologically, it just doesn’t lead to knowledge. However what I find more important is to point out what just occurred. We were both playing the same game by the same rules, attempting to prove our views with logic and evidence, but as soon as it became apparent the skeptic had defeated the logic and evidence of the believer, the believer changed the rules of the contest. Now you can’t stop people from doing this but you can try to make them acknowledge that to withdraw from the use of reason purely when it doesn’t fit them anymore is an admission that the belief they hold isn’t rationally based, or at the very least they are currently out of rational reasons and should permanently stop using those arguments just refuted.
In moral terms abortion, same-sex marriage and the death penalty are all subject to faith claims on all sides of the issue. So if someone is to reasonably decide if any of these are moral we must clearly reject faith as a guide to do so. Still, for example, Obama’s support of same-sex marriage today will undoubtedly be met with claims of immorality based solely on the fact it contradicts a faith position that homosexuality is immoral. As my previous post indicated, I don’t buy for a moment any arguments that homosexuality is immoral but because morality is one of last places in public discourse where it is still acceptable to use religious beliefs as the sole justification for a position. As a result people who oppose same-sex marriage largely don’t even bother to make arguments to support their position.
However in science, where creationism and a small minority of climate change deniers disagree with established science because of their religious beliefs, it’s no longer publicly acceptable, at least not in political or legal discourse, to replace argument with an explicit expression of faith. When people do this they are roundly dismissed as unfairly, and unconstitutionally, attempting to force their religious beliefs onto secular society. Now there aren’t any moral positions supported the way the theories of evolution and climate change are, but I think secular people must be just as vigilant in pointing out the unfair and unconstitutional move from using reasoning and evidence to faith positions with regard to morality as they are about issues of science. It’s our responsibility to remind them either that retreat into faith should be allowed in every field, which would make rational discourse impossible, or it shouldn’t be allowed anywhere.
Should Interracial Marriage Be Banned?
If anyone thinks these are good arguments to ban same-sex marriage then they were good arguments to ban interracial marriage.
As for a production note: I was thinking of creating a list like this but it seems I was beat to the punch… by 12 years. eQuality Giving had already compiled such a list so I made this simple image instead.
“When someone says ‘I have these two crystals if you rub them together you’ll get healthy.’ Rather than just discount it—because that’s as lazy as accepting it, both of those are just lazy brain—what you should do is inquire. So do you know how to inquire? Every scientist would know how to start that conversation. They would say ‘Well where did you get these? What kinds of ailments does it cure? How does it work? What does it cost? Can you demonstrate that it works?’ And you go through this… And at the end the person is in tears because they weren’t prepared for that level of questioning. So science literacy is vaccine against charlatans of the world that would exploit your ignorance of the forces of nature.” — Neil de Grasse Tyson - on the nature of scientific inquiry
(Source: youtube.com)