Don't Question This!

In all affairs, it’s a healthy thing now and then to hang a question mark on the things you have long taken for granted. Bertrand Russell

I’ve always been taught that you don’t question that. How many times have you heard someone say this especially about their religious belief? But, isn’t this an unfortunate lesson to be taught? Would you teach your children not to ask questions? I would hope not but I suspect that many do in fact teach this quite harmful lesson.

What is so wrong about teaching the lesson not to ask questions?

First, it breeds a lack of curiosity. After all, why be curious about a subject if you have been taught not to question it. For that matter, why be curious about most subjects. Since you can't be quite sure that you ought to be asking questions about these areas as well it's probably best to play it safe. One never knows what trouble you might get into by being curious!

Second, it gives the misleading impression that we don’t have explanations for many phenomena for which we do have explanations. Without a sense of curiousity and what Bertrand Russell called the "will to find out," we miss out on discovering the truly fascinating explanations we do have for the world around us and why things are the way they are. For most of these areas explained by theories such as relativity, quantum mechanics, and evolution, the explanations we do have are much more fascinating than the explanation given and followed by "we don't question this."

The third problem with teaching the lesson not to ask questions is that it makes one vulnerable to demagogues and highly dubious claims. The heart of good critical thinking is the ability to ask the right questions and seek out evidence. In some cases, it is useful to be able to demand of others making claims that they validate these claims before we assent to them. But, the lesson of not asking questions undercuts these critical thinking skills. The price you pay for this is to be left vulnerable to any number of dubious claims. Think of how many of these claims you are exposed to each and every day from politicians, advertisers, lawyers, ministers, actors, CEOs, and many others. They all want you to believe the claims they are making and they all hope you don't ask too many questions.

A fourth problem with teaching the lesson not to ask questions is best explained by Richard Dawkins who calls it quite simply child abuse: “To slap a label on a child at birth - to announce, in advance, as a matter of hereditary presumption if not determinate certainty, an infant’s opinions on the cosmos and creation, on life and afterlives, on sexual ethics, abortion and euthanasia - is a form of mental child abuse.” What does he mean by this? I suspect in part his point is the point I have been trying to make in this post.

Parents teach by their actions even more than their words. If you want your children to be good critical thinkers you have to model this behavior. Likewise, if you model the behavior of not asking questions your child will learn this lesson. Is your reaction to this claim relief? Are you saying to yourself "Ah, good I was hoping to be able to teach my child that we don't ask questions about such important ultimate areas of human life?" If your answer to these questions is "yes" then there's really nothing left to say. But, if your answer is no then it might be time to begin asking questions where you have not been asking them before.

You Gotta Have Faith!

Every sect, as far as reason will help them, gladly use it; but when it fails them they cry out that this is a matter of faith, and above reason.
John Locke


I respect faith, but doubt is what gets you an education.
Wilson Mizner


A favorite response from students when confronted with the search for evidence related to philosophical questions (especially the question of God’s existence) is to look towards faith. If they believe there is no evidence that can substantiate their belief in God their response is “that’s why you have to have faith.” But, when you think about it this is an odd response. In no other area of life could this possibly make sense but for their belief in God they seem to think it does. How would we respond to someone researching cold fusion for example who when presented with the lack of evidence in the phenomena simply responds by saying “well, that’s why you have to have faith.” Why do we have to have faith in something that is not validated by evidence?

I don’t have a truly satisfying answer to this question but I would like to hear from some who say this about their reasoning behind the claim. I can guess at some possible explanations which I put forward below but these are only guesses.

A common justification for having faith might be that one has to believe in something. But, this misses the possibility of believing in something that is validated by evidence. If the need to believe is strong isn’t it also accompanied by the desire to believe what is true? While we don’t have any guarantees that our current explanations for how the world works are absolutely true we do have enough validating evidence to warrant belief. And, given the evidence belief in these explanations is surely much more justifiable than belief in something which utterly lacks validating evidence.

Another possible justification for belief could be that it is comforting. This justification could help explain the objection raised above that one should believe according to the evidence. People may not want to believe in explanations that are validated by evidence because they are not comforting. An explanation that asserts that we are all loved by a supreme being who has a plan for us may be more comforting but does that make it true? Surely not. But, then how comforting can it be to believe in something one suspects may not be true?

But, maybe that’s just it. Faith tells the believer that what they believe in is true never mind what their doubts or the evidence might indicate. Faith allows one to push on through that doubt by making a virtue of the lack of evidence. As Tertullian said “it is certain, because impossible.” This sounds immediately satisfying to the believer unless they make the mistake of asking a very ordinary and reasonable question. Does this rule of believing because something is impossible only apply to religious beliefs or can it be applied to other areas of life? If the answer comes back that it only applies to religious beliefs the next question is: Why?

Why can’t we apply this to other equally important areas of life including our relationships with others, our healthcare, our careers? It would clearly be absurd to apply this rule to these areas of life but why does it apply to an area of life which purports to explain such ultimate questions as the origin of the universe and life on Earth; questions for which we have quite plausible (not to say possible) explanations? Why does the belief in God need to obvious crutch of “believe because it is impossible.” Something to think about.

What's wrong with faith?

Many of those who are engaged in the evidence forum here or in my philosophy course will likely be wondering this as we go through the semester looking for evidence beyond one's own faith concerning these questions. But, what's wrong with basing our beliefs solely on faith without worrying about evidence?

Well, there are several things wrong with this. First, it ignores the possibility that there is relevant evidence. By skpping the search for evidence and going straight to faith we might be missing some useful information and interesting insights.

Second, it is important to remember that even the most faithful of philosophers and theologians have recognized that it is important to ground their faith in reason, evidence, and knowledge. This is why St. Thomas Aquinas offered five ways for proving the existence of God for us to examine.

Third, if you concede that faith is all that is required when it comes to drawing conclusions about one of these questions we're addressing (probably the one about God) why not concede that faith is all that is required for drawing conclusions about the other questions as well? You might respond by saying that for those other questions there is evidence whereas for the question of God's existence there is none so we have no recourse but to rely on faith. Which brings me to:

Fourth, if all we have to go on is faith and no evidence how do we know what to believe with regard to one or any of these questions. By definition, without evidence or objective facts to draw on, everyone is right about what they believe no matter what this might be. What is the problem with this? It illustrates that the belief (in this case about God's existence) is not really a belief about how the world is but about what the believer feels. This is fine as far as it goes but most believers do think that their beliefs say something about how the world really is as opposed to merely how they feel.

So, the search for evidence is important. What if that search fails to find any evidence? There are several responses one can make.

Believe whatever you want anyway.
Suspend belief entirely.
Believe what the evidence allows and nothing more.

Of course, you are free to choose which of these options you wish. Two important final points seem relevant though. David Hume once said that "the wise man proportions his belief to the evidence" and Christopher Hitchens has been quoted as saying "what can be asserted without evidence can also be dismissed without evidence."

The Baloney Detection Kit

You can watch the video here: http://www.michaelshermer.com/2009/06/baloney-detection-kit/.

The Ten Questions:


How reliable is the source of the claim?
Does the source make similar claims?
Have the claims been verified by somebody else?
Does this fit with the way the world works?
Has anyone tried to disprove the claim?
Where does the preponderance of evidence point?
Is the claimant playing by the rules of science?
Is the claimant providing positive evidence?
Does the new theory account for as many phenomena as the old theory?
Are personal beliefs driving the claim?

Does it make a difference?

When it comes to the philosophical questions we pose here a popular claim is that there really is no evidence that we can gather to answer them. This is an especially popular reaction to the question: Is there a God? But, let's think about this for a moment.


Let's suppose that there is no evidence of any kind to count either for or against the question of God's existence. Then whether God exists turns out to be true or false is not a matter of how things are in the world. The claim that God exists is simply a claim about how the person who believes feels. Likewise, the claim that God doesn't exist is simply a claim about how the person who does not believe feels. Is this really what you want to maintain when it comes to this question? To the believers we could ask: Do you mean to say that your claim that God exists has no bearing on how things are in the world? If you don't believe there is evidence then you must answer this question yes. However, if you think that God's existence makes some difference to the world and how it works then you have to concede that evidence is relevant to answering the question.


Why is this such a hard thing to concede? I believe it is because recognizing the relevance of evidence means that you have to recognize the relevance of all the available evidence not just the evidence that validates your position. This involves risk.


It is easy for most believers to cite some evidence for their belief; personal experiences, miracles, the complexity of the world. What is more difficult is to evaluate this evidence in light of good standards of critical thinking. Indeed, there are problems with citing personal experiences or miracles as evidence and we can discuss these in later posts. The notion of the complexity of the world has been discussed in many forms but essentially comes down to one form or another of the teleological (or design) argument which we can also discuss in later posts.


The point to make here is simply that if God's existence matters, if God's existence makes a difference in the world then evidence has to be relevant to the question and that evidence exists. Our goal here is to find the evidence and evaluate it. As Bertrand Russell once said "what we need is not the will to believe, but the wish to find out."

The Argument Clinic

Think you've got a good argument that hasn't been sufficiently addressed? Or perhaps you just want another analysis besides the one offered by your instructor. Then you might enjoy trying this website: The Argument Clinic. You can submit arguments and they will analyze them and inform you of their philosophical merits.

Drawing conclusions before the evidence is in

I wanted to make the Evidence forum available for students to begin thinking about the concept of requiring evidence for these philosophical questions as this process may be new for many. Many students have already begun to post comments to the discussion. However, for some of the questions (such as the question of God's existence) it seems premature to draw conclusions before even researching or learning about the available evidence. But, this does illustrate an interesting philosophical point. Notice how easy it is to draw conclusions and form beliefs without collecting any evidence or knowing about the efforts put in to do just that!

Don't misunderstand. I'm not saying that once everyone reads what we cover in this course which relates to these questions the evidence will clearly indicate what the answer is to each of these questions. But, making pronouncements without examining any of the evidence is not philosophically sound. What if you were going before a judge in a court case and as the trial begins the judge comes in, calls everyone to order, and then issues the ruling without hearing any evidence? Wouldn't that seem wrong? Likewise, I think we're jumping the gun in our examination of these questions as well.

It may turn out to be true that there is no way to provide proof or evidence for any of these questions but, again, how can we draw this conclusion before examining the evidence? It is all too easy to believe any number of things about these questions, including that they cannot be answered. But, as Bertrand Russel once said "What is wanted is not the will to believe, but the wish to find out, which is the exact opposite."

Another purpose of the Evidence discussion board is to help everyone (including me as my own reading and research is ongoing with regard to these questions) recognize that there is a lot of background knowledge that one really needs to be familiar with before drawing conclusions about these questions. One of the purposes of this course is to introduce students to this background knowledge and its effects on our understanding of the world around us.

While there are still many unanswered questions with regard to the evidence that relates to these questions, there is quite a bit that we do know concerning how the mind/brain works, how we gain knowledge, the fundamental structure of reality (thanks to relativity and quantum mechanics), the origin of the universe, the age of the earth, the natural history of life on earth. Aside from the fact that this is useful information in our quest to answer these questions, it is also really interesting! Let's all take this opportunity to be curious and learn about these things!

The Concept of Proof (part 2)

Now, for the payoff of our discussion in part one of the Concept of Proof. While many may hate to hear this, judging by the criteria outlined there, the theory of evolution and the big bang theory do quite well. In fact, as the philosopher Daniel Dennett puts it "evolution is about as well established as the fact that water is H2O." This doesn't mean that the theory isn't open to revision. But, all available evidence seems to point in favor of it. A similar statement could be made about the big bang theory again, with the proviso, "at this time." So far as we know now. This will always be the case for any theory in science. As Karl Popper pointed out, "the demand for scientific objectivity makes it inevitable that every scientific statement must remain tentative forever."


So, why do people find this a hard pill to swallow about the theories I mentioned above. I suspect it's because they do not know about them and based on this lack of knowledge they conclude that these theories do damage to some of their cherished beliefs. No book has been more reviled since its publication that Darwin's Origin of Species. But, I suspect no book has been left unread as often! Scientists have no problem with entertaining objections to their theories, but the objections should be based on some knowledge of the theory. I cannot devote myself here to explaining in sufficient detail the theories I'm addressing though I could if put to the test. But that is not the point of this essay.


My point, as a philosopher, is to encourage learning and inquiry. But first comes the learning. To be sure, philosophers are all too willing to subject other philosophers to criticism. But they do so from the standpoint of understanding their opponent's theory. We owe the same to any theory be it in philosophy, theology, or science. It does no good to criticize or dismiss a theory out of hand without a thorough understanding of what the theory says and what phenomena it is attempting to explain.


Many say they do not believe in the theory of evolution or the big bang. But the word "believe," like the word "proof," is being misused here. A theory is not something to be believed or disbelieved. The question is whether the evidence warrants our tentative acceptance of the theory. Does the theory do what it claims to do? That is, does it provide us with an adequate explanation of the evidence at hand? If so, it's a good theory. You are certainly free to think otherwise but this doesn't change the fact that the theory is supported by the evidence.
Of course any theory may turn out to be wrong but as David Hume said "the wise man proportions his belief to the evidence." If the evidence warrants it, the theory should be accepted.



This does not amount to conceding everything to the world of science because there are many questions science cannot answer. These include questions of value and meaning such as:


Does my life have a purpose?

Does the universe's existence have a purpose?

Is abortion immoral?

Is it ever right to lie?


Here is where the value of philosophy lies because it is philosophy that attempts to examine these questions and reason to useful answers. Not necessarily definitive answers. There may be no definitive answers to these questions. But, we can examine them in the light of reason and come to some interesting conclusions. But, these conclusions can be furthered by the work scientists do as they attempt to explain the natural world in which we live. After all, asking about the purpose of our lives is a question that can be dealt with much better if we have some understanding of life. To ask whether the universe's existence has a purpose can be answered in a clearer way if we have some understanding of the universe itself. It is misguided to reject the information that science gives us which may pertain to these and other questions. The scientific method is, after all, the most reliable means we have of gaining information about the natural world. Information, without which, we would not be able to philosophize with any sophistication at all.


Finally, don't accept the conclusion of an argument just because you like it and don't reject the conclusion just because you dislike it. In each case, you need to consider the reasoning used and determine whether the conclusion is supported by the premises and whether the premises are true. Wanting something to be true does not make it true and wanting something to be false does not make it false. The questions we examine can be difficult questions but applying the rules of reason can make our job of evaluating philosophical arguments easier and more fruitful.

The Concept of Proof (part 1)

"We cannot pretend to offer proofs. Proof is an idol before whom the pure mathematician tortures himself: In physics, we are generally content to sacrifice before the lesser shrine of plausibility." Arthur Stanley Eddington


Proof is a seriously misunderstood word. This probably accounts for its rare usage in the natural sciences. In one important sense no one can "prove" the theory of evolution, or the big bang theory, or relativity, or string theory, or whatever theory you want to talk about. But, and this is an important but, that does not mean that there is not sufficient evidence to warrant thinking these are good theories. To use Eddington's word, we can say they are plausible. In some cases, very plausible. What makes the word proof tricky is that it is sometimes used in philosophy in the one area you'd think everyone would be wary of using it: to prove the existence of God. Many people believe that God's existence cannot be proven. Let's stipulate to that for the sake of argument and vow only to use the word proof in areas where certainty appears attainable, like mathematics. The parallel postulate can be proven.


So what do we do with areas of empirical research? What do we do about God? Let's look for evidence and evaluate theories based on their plausibility and efficacy in explaining and accounting for that evidence. We need a set of criteria to evaluate theories to determine which best account for the evidence we have. A good suggestion comes from a critical thinking text titled How to Think About Weird Things by Theodore Schick and Lewis Vaughn. In it, they outline five points to use in the evaluation of theories. Let's look at them.


First a theory should be testable. If you can’t even figure out how to go about determining if your theory explains the evidence you don't have a good theory. As they point out testable means your hypothesis "predicts something more than what is predicted by the background theory alone." In short, we need this criterion because if there's no way to tell whether a theory is true or false it's really no good to us.


Second, a theory should be fruitful. What this means is that a good theory should make novel predictions. It should not only account for the evidence at hand but be able to address evidence that comes in later and even predict such new evidence. They point out that Einstein's theory of relativity is a good example of a fruitful theory because it made the novel prediction that light would be visible from a star behind the sun because the light would be bent by the gravitational field around the sun to be visible on earth. And, with reference to criterion number one this was a testable claim. Once tested, it was verified.


Third, a theory should have a wide scope. That is, a good theory explains a wide field of evidence. One of the differences between theories and hypotheses is their scope. Hypotheses address specific questions whereas theories attempt to provide a broad explanatory device. Theories that can explain a wide array of things are preferred, other things being equal, to more narrow theories.


Fourth, a theory should be simple. This term should not be confused with simplistic. Many scientific theories are complex in terms of our ability to understand them but simple in the sense that they postulate fewer underlying entities or assumptions. A good example of this is the difference between Copernicus and Ptolemy. Ptolemy's geocentric theory could explain the orbits of the planets but it was quite complex whereas Copernicus' theory explained the same observable phenomena with less complexity. So, other things being equal, that theory was the better theory. Think of it this way. Suppose I come up with a theory to explain how the lights in my house work but it involves little gremlins running inside the light bulbs. Someone else is able to explain the same phenomenon but without postulating gremlins. So, their theory is simpler than mine. It should also be pointed out that my gremlin theory may fail on other criteria as well such as being testable.


Finally, a theory should be conservative. Not in the political sense of the word. Rather, it should fit in with other things we know. If we have an explanation for something that we think is fairly certain and accurate then a new theory should fit in with that prior explanation. If it doesn't fit that may indicate our prior knowledge is flawed. We have to be open to that possibility but the burden of proof is on the new theory.

Thoughts and Feelings

“A great many people think they are thinking when they are merely rearranging their own prejudices." William James

All throughout the history of philosophy there have been philosophers who have written about emotions in an effort to understand, and in some cases, control them. Plato, Aristotle, the Stoics, Epicurus, Descartes, Hume, Sartre are just a few who have inquired into the nature of emotions. In ethics there is a theory which claims that moral statements are nothing but the expressions of one's emotions.

But, the point of this essay is not to defend the philosophical investigation of emotions. Instead, I would like to encourage a distinction between thinking and emotion in one limited sense. While philosophers investigate many questions, in their formulation of theories they are usually attempting to tell us what they think about a subject not how they feel. There is a good reason for this which I would advocate when you write about philosophy or any other academic subject. As you write an academic paper bear in mind that in most cases the assignment is to formulate your thoughts and defend them. It is not to tell your professor how you feel. It is certainly not to tell your professor how others feel.

This may seem like a purely semantic point. Perhaps when you use the word feel you're really meaning to state what you think. But, words do have meanings and it is important to recognize important distinctions, such as the distinction between thinking and feeling. The most important difference between the two words and the sentiments behind them is that one requires justification and the other does not. When I tell someone what I think it is fair for them to ask me why I think this. What evidence am I presenting to back up my opinion? Is the evidence persuasive and complete or is it inadequate to verify the claim I am making? This is not the case with feelings. If I tell someone I feel hot I do not have to justify this feeling. In fact, it would seem strange for someone to demand of me any justification for this or any other feeling. My feelings are what they are. And as many psychologists will tell you, they are neither good nor bad and neither true nor false.

The problem with referring to feelings in philosophy in the way I am criticizing is twofold. First, it is likely inaccurate. When you say something like "Plato felt that there was a realm of the forms" you are not really accurately depicting Plato's feelings at all. How could you? We don't know what Plato felt about the Forms since he never told us! However, we do know some of what he thought about the Forms and if I ask you an exam question about Plato's theory that is what I want you to tell me: what Plato thought, not what he felt. Second, to claim that Plato merely felt a certain way about the Forms is to diminish the philosophical exercise the philosopher was engaged in.

The attempt to formulate a theory about something is simply an attempt to take the available evidence and provide the best possible explanation for it. In doing so, the philosopher attempts to anticipate possible objections to his explanation and address them. The philosopher is also prepared to defend his theory in the court of public opinion and allow his theory to be subjected to criticism and debate. If it were nothing more than a feeling, there would be no need to scrutinize it at all. In fact, there would be no interest in it at all!

When you write a philosophy exam or paper (or any other paper) you will be asked to explain your views or opinions. You will not be asked to describe how you feel. So, as harsh as this sounds, don't tell me how you feel! Don't tell me how the philosophers you are writing about feel either. Tell me what they thought and why they thought it. Tell me what you think and why you think it.

It is fine to express opinions but you must also explain why you hold these opinions and, more than that, explain why you think your opinions are correct. Many seem to confuse what philosophers do by saying that they just express their opinions. In fact, philosophers do more than this by backing up their opinions with reason. This is the crucial distinction between arguments and opinions. Arguments can contain opinions but to argue for something is to do more than simply express an opinion or a feeling about something.

I find it remarkable how some people can be very tentative with regard to their opinions. This occurs most often in the realm of opinions concerning morality. Someone believes abortion is immoral but doesn't think others should believe this as well. Students will say that everyone has their own beliefs. Of course, this is quite true but the question is, "Are these beliefs justified?" This is why we need to examine the reasons behind the opinions. If the opinions are not justified then no one should hold them. On the other hand, if the opinions are justified and backed up by good reasons, shouldn't everyone agree with them?

To this many will respond by asking "But, who am I to tell someone else their beliefs are wrong?" The point is that you are not telling them because you are not examining their beliefs; they are! One of the useful skills you can take from any philosophy course is a method for examining your beliefs and justification for them. The point of the examination is not necessarily to change your beliefs although if you discover they cannot be justified perhaps they need to be changed. It could easily be the case that you find a stronger justification for them than you suspected even existed. In any case, it is the examination that is valuable. We are always being encouraged to examine our feelings. While philosophy is not unconcerned with feelings, the main point of philosophy is to allow us to examine our thinking.

Another way of looking at this is that the examination of one's beliefs is done by appealing to objective criteria we can use to determine whether our beliefs are justified. They are important to understand in order to successfully examine one's beliefs and opinions and quite easy to understand with a little work. However, the fact that this takes work at all probably explains why many prefer to simply talk about feelings. There's no work involved in justifying feelings because feelings don't need justification!

Is knowledge innate or learned from sense experience?

Here are some books with relevant information concerning this question:

Immanuel Kant The Critique of Pure Reason
Steven Pinker The Blank Slate
Steven Pinker The Stuff of Thought
Keith Lehrer Theory of Knowledge
Michael Goodman Contemporary Readings in Epistemology
Morton Hunt The Story of Psychology

Is the mind independent of the brain?

Here are some books with relevant information concerning this question:

Rene Descartes Meditations on First Philosophy
Jeffrey Schwartz The Mind and The Brain
Antonio Damasio Descartes' Error
Steven Pinker How the Mind Works
David Chalmers The Conscious Mind
Paul Churchland Matter and Consciousness
John Searcle Minds, Brains, and Science
Carl Zimmer Soul Made Flesh
Steven Johnson Mind Wide Open
Pierce Howard The Owner's Manual for the Brain
Evan Walker The Physics of Consciousness

Is there an objective reality independent of sense experience?

Here are some books with relevant information concerning this question:

Immanuel Kant The Critique of Pure Reason
Brian Greene The Elegant Universe
Michael Shermer Why People Believe Weird Things
Andrew Newberg Why We Believe What We Believe
Thomas Nagel The View From Nowhere
Jerome Shaffer Reality Knowledge and Value
Robert Nozick Invariances The Structure of the Objective World

Is there a God?

Here are some books with relevant information concerning this question:

Mortimer Adler How to Think About God
Robert Wright The Evolution of God
Richard Dawkins The God Delusion
John Allen Paulos Irreligion
John Hick The Existence of God
Jack Miles God A Biography
Bernard Haisch The God Theory
Michael Corey The God Hypothesis
Gerald Schroeder The Hidden Face of God
Andrew Newberg Why God Won't Go Away

Evidence F.A.Q.

Q: What are you trying to do with this blog and website?

A: Simply put we are trying to assemble in an orderly fashion the relevant evidence for the philosophical questions posed. This will be a helpful resource for coming up with answers for some of these ultimate questions.

Q: But, isn't evidence irrelavant to philosophical questions?

A: Not at all! In the case of the four questions posed on the website they each ask about some aspect of how the world is. As such, the answers to these questions (no matter what they end up being) will make empirical claims about the way the world is. Thus, evidence is very relevant to validating these claims.

Q: Why do you avoid Socratic questions such as What is love? What is beauty? etc.

A: These questions are important philosophical questions but do not as easily lend themselves to a search for empirical evidence. For more insight on these questions I would encourage you to go to the companion website Ask-A-Philosopher.

Q: Why do you avoid questions about ethics and morality?

A: These will be dealt with in a separate website coming sometime in 2010.

Q: How do I contribute to the search for evidence?

A: Simple, you can make posts here to the questions or e-mail us via the Evidence website and we will post your comments here for consideration.

What counts as good evidence?

Since this is a search for evidence that will help answer ultimate questions, we need to consider relevant and valid evidence. A good start is the following critical thinking guidelines from a book titled How to Think About Weird Things:

• Just because something is logically possible doesn't mean that it's real.
• Just because a claim hasn't been conclusively refuted doesn't mean that it's true.
• Just because a claim hasn't been conclusively proven doesn't mean that it's false.
• Just because you can't explain something doesn't mean that it's supernatural.
• Just because something is physically possible doesn't mean that it's real.
• Just because something seems (feels, appears) real doesn't mean that it is.
• Just because you believe something to be true doesn't mean that it is.
• Just because a group of people believe that something is true doesn't mean that it is.
• There is an external reality that is independent of our representations of it.
• There is good reason to doubt a proposition if it conflicts with other propositions we have good reason to believe.
• The more background information a proposition conflicts with, the more reason there is to doubt it.
• When there is good reason to doubt a proposition, we should proportion our belief to the evidence.
• There is good reason to doubt a proposition if it conflicts with expert opinion.
• Just because someone is an expert in one field doesn't mean that he or she is an expert in another.
• If we have no reason to doubt what's disclosed to us through perception, introspection, memory, or reason, then we're justified in believing it.
• When evaluating a claim, look for disconfirming as well as confirming evidence.
• When evaluating a claim, look at all the relevant evidence, not just the psychologically available evidence.
• A hypothesis is scientific only if it is testable, that is, only if it predicts something other than what it was introduced to explain.
• Other things being equal, the best hypothesis is the one that is the most fruitful, that is makes the most novel predictions.
• Other things being equal, the best hypothesis is the one that has the greatest scope, that is, that explains and predicts the most diverse phenomena.
• Other things being equal, the best hypothesis is the simplest one, that is, the one that makes the fewest assumptions.
• Other things being equal, the best hypothesis is the one that is the most conservative, that is, the one that fits best with established beliefs.
• We should accept an extraordinary hypothesis only if no ordinary one will do.
• Personal experience alone generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• Case studies alone generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• When claims of a treatment's effectiveness are based solely on case studies or personal experience, you generally cannot know that the treatment is effective.
• Scientific evidence gained through controlled experiments, unlike personal experience and case studies, generally can establish the effectiveness of a treatment beyond a reasonable doubt.
• Single medical studies generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• When the results of relevant studies conflict, you cannot know that the treatment in question is effective.
• New study results that conflict with well-established findings cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• Test-tube studies alone generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• Animal studies alone generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• Observational studies alone generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.
• Clinical trials limited by lack of a control group, faulty comparisons, or small numbers generally cannot establish the effectiveness of a treatment beyond a reasonable doubt.