My friend Ed Gibney has written on each and every one of the thought experiments in  Julian Baggini’s, The Pig That Wants to Be Eaten: 100 Experiments for the Armchair Philosopher. He has also summarized his own100 blog posts on Baggini’s 100 thought experiments in “What I learned from 100 Philosophy Thought Experiments.”

(Here is his summary of, and commentary on, Baggini’s thought experiments dealing with metaphysics. It follows from a previous post on ethics. I have added my own brief reflections at the bottom of the page.)

From Ed Gibney’s blog, reprinted with permission.
http://www.evphil.com/blog/what-i-learned-from-100-philosophy-thought-experiments

5. Aesthetics

In #48 Evil Genius, we see now how ethics and aesthetics can be united. Beauty is good; it is that which promotes the long-term survival of life. Bad art, no matter how well it is executed, is blind emotion that purports falsehoods for truth. #37 Nature the Artist helps us understand that this idea of beauty is objective to reality, but the beauty of any object is subjective to the considerations of each specific observer. That is how we make sense of the confused and competing definitions of beauty and art that exist at present. But in #86 Art for Art’s Sake, we see that artistic objects have no intrinsic worth on their own; they are not a form of life. Art must provoke emotions in someone (even if it is just the artist) in order to be considered art. And therefore, as in #66 The Forger, a true connection to the emotions and knowledge of an artist undoubtedly adds an extra dimension to any work of art, and that dimension can even become priceless whenever such a connection is deemed irreplaceable and full of inspirational beauty. When such art impels us to grasp for good lives, we reach out to those around us in order to actually accomplish it. And that leads us to the final branch of philosophy in our worldview.

My brief reflections – I probably know less about aesthetics than any other branch of philosophy. Let me just say that there is something about beauty that is intrinsically worthwhile. Truth, beauty, and goodness are the 3 great ideas by which we judge things. Here I’ll quote from Bertrand Russell’s last manuscript:

“There is an artist imprisoned in each one of us. Let him loose to spread joy everywhere.”

(Next up – the thought experiments dealing with political philosophy.)

My friend Ed Gibney has written on each and every one of the thought experiments in  Julian Baggini’s, The Pig That Wants to Be Eaten: 100 Experiments for the Armchair Philosopher. He has also summarized his own100 blog posts on Baggini’s 100 thought experiments in “What I learned from 100 Philosophy Thought Experiments.” 

(Here is his summary of, and commentary on, Baggini’s thought experiments dealing with metaphysics. It follows from a previous post on metaphysics. I have added my own brief reflections at the bottom of the page.)

From Ed Gibney’s blog, reprinted with permission.
http://www.evphil.com/blog/what-i-learned-from-100-philosophy-thought-experiments

4. Ethics

The most commonly cited source for human ethics today is religion. This invention is understandable because it fills the void of our longing to know how to survive in our inherently uncertain universe. As seen in #58 Divine Command, when environments are filled with harsh adults who are unable or unwilling to explain themselves, children learn to obey to survive. This can easily lead to a perpetual cycle as these children also learn to dominate when they can, and they don’t learn to think clearly on their own.

However, #95 The Problem of Evil shows that Gods have all just been made up ideas, and the particular one invented and followed by Judaism, Christianity, and Islam—the one that is supposedly omnipotent, omniscient, and all-loving—is a logical impossibility given the facts of the world. #45 The Invisible Gardner illustrates how scientific discoveries have made the gods of the gaps vanishingly small. Poof. In fact, according to #8 Good God, no gods tell us what is good; we determine it ourselves. In #78 Gambling on God, religious answers for epistemology and logic have been shown to be flat-out wrong and dangerous. They must be discarded. All of the good benefits of religion can be provided by a secular worldview.

So what are the secular sources of ethics? Traditionally, in philosophy, as in #60 Do As I Say, Not As I Do, we see how any morally considered human behavior has an intention, an action, and a result. That’s the way an event is described prior to, during, and after it occurs. It’s the way the past, present, and future are bound together by causality yet allowed to be looked at separately across time. Virtue ethics concerns itself with the intention behind an act. Deontology focuses on the action alone. [Kant’s deontology focuses on intention too.] Consequentialism focuses on the result. But all three may be evaluated individually for moral purposes. Also, #71 Life Support points out that neglecting to act is still an act that can be morally judged for intentions and consequences.

Exploring these philosophical options, deontological rules and universal virtues don’t work by themselves because sometimes, as in #7 When No One Wins, it’s possible to do long-term good by doing short-term bad. Even further, as in #99 Give Peace a Chance?, more deaths over the short-term may be preferable to more misery and death over the long-term, although empirically it’s not very easy to know the difference ahead of time, and I personally am very glad that my best course of action hasn’t involved such sacrifice. The most universally known deontological rule is #83 The Golden Rule, but the Golden Rule is simply calling for reciprocity, for empathy, for more cooperation. But this isn’t enough! Cooperation towards what? Putting a bagel on Saturn? Subjugating ladybugs? Spreading the message of Moses? It’s terribly misguided to focus on means without considering ends too.

Consequentialism or utilitarianism tries to focus on ends, but historically they have only considered well-being, pleasure, or avoidance of pain as the ultimate goal. #84 The Pleasure Principle, however, shows that pleasure or freedom from pain are not ends in themselves, they are means towards something else. They are signposts for how to act towards survival. #98 The Experience Machine says the best prospects for long-term survival and well-being lie in dealing with the real world. Pleasure or pain avoidance are merely proximate goals in service of an ultimate goal, they are not intrinsically or inherently valuable or costly on their own. This is partly why utilitarianism fails. In #89 Kill and Let Die, we see another reason is because human evolution, as well as the evolution of other advanced animals, is governed to a greater or lesser extent by a mix of genetic and cultural traits, so the practically unknowable value of one unique human to the cultural evolution of our species means we cannot weigh life and death trolley-problem decisions by using some simple rule such as “one human = one human.”

According to #96 Family First, the equal weighting of persons or sentient creatures in the theoretical mathematics of utilitarianism doesn’t hold up in the real-life decision-making of individuals because we are not indistinguishable widgets that can be perfectly substituted one for another. While all human beings originally have equal standing for moral claims, the actual force of their claims on us is variable depending on many things such as our ability to satisfy their claims, their reputation from prior actions, or their possibility of reciprocating aid over repeated interactions in the future. In other words, as in #22 The Lifeboat, moral concerns are a force that behaves somewhat like gravity with stronger pulls by larger bodies at close distances often overshadowing the background tugs of fainter objects far away, and moral actions get harder to determine the farther away their actions are directed.

So prior sources of ethics all have problems. It’s okay to discard these old values though since we see in #27 Duties Done that oughts must be derived from more than just current norms of oughts. In #50 The Good Bribe, we see that in order to truly consider “the big picture” of a moral decision, you must look at the largest and longest view of life. In #100: The Nest Café, we see that due to the deep interrelatedness and interconnectedness of all living things, hierarchies of needs ought to be considered for each and every form of life. This includes all seven areas of E.O. Wilson’s consilient view of life: 1) Biochemistry → 2) Molecular Biology → 3) Cellular Biology → 4) Organismic Biology → 5) Sociobiology → 6) Ecology → 7) Evolutionary Biology.

Thus, as described in #52 More or Less, evolutionary ethics are based upon a deontological rule — “good is that which enables the long-term survival of life” — and that gives us an objective and universal consequence towards which we ought to act using virtues derived from evolutionary studies that scientifically prove to us which traits are successful in leading life towards that goal. We may not be able to answer any ultimate questions now of why the universe and life exist, but maybe someone will be able to someday, and it is our job to do what we can to get to that day. Therefore, the number of people and the quality of their lives ought to exist within some range that balances scientific progress against existential robustness.

To clarify, in response to someone Questioning All This, too little life in terms of quantity, quality, or diversity is a fragile state, and too much life full of overcrowded, competitive, misery is another fragile state. Evolutionary ethics looks for robust optimization in the middle where well-being is also optimized, but this is only reached by recognizing that comfortably assured survival for life is the ultimate goal. The only position that contradicts this would be an argument for universal death, but that is an argument we living beings reject. Once you agree that any part of life ought to continue, then you agree that life, in general, wants to continue and we are then down to questioning the details of how that works, which is an empirical question. So, therefore: 1. Life is. 2. Life wants to survive. 3. Life ought to act to survive. By discovering this objective basis for morality, we can examine history and see how the moral values of humans have grown and changed over time and we can try to judge them using the meta-principles of what we see best survives over the long-term during evolutionary processes.

Okay. That is what “good” is, but how do we live a good life?  What does this mean for me, for individual flourishing, or for what the Greeks called eudaimonia? We want to be happy and to feel pleasure, but we must recognize, as in #26 Pain’s Remains, that pain in life is unavoidable, and may, in fact, be necessary for all of the wisdom and empathy it gives us. Pain is a useful signal. Further, #91 No One Gets Hurt shows how we carry a host of biochemical “side effects” from our evolutionary history. We have freedom and flexibility to overcome many of them, but they cannot be completely forgotten. When one knows that some part of their actions are bad they will be subject to feelings of guilt. In #76 Net Head, we see that these guilty feelings or other perpetual feelings of anger are sure signs that your worldview isn’t working. They come from cognitive appraisals that “something is bad and I need to do something about that.” That “something bad” is either the world or your worldview.

From #68 Mad Pain, it is obvious that we humans feel pain when flesh and bones are torn apart, but perhaps we can feel physical pain when neuronal connections are torn apart as well. This would explain the observations that any challenge of a basic assumption will release anxiety and defensiveness. Such challenges painfully tear our minds apart. But ripping off the duct tape that holds most worldviews together seems much more preferable than feeling the continual anxiety that seems to arise when most worldviews are faced with evidence from the real world. In #61 Mozzarella Moon, we see that speaking in a debate probably moves too quickly to change deeply held beliefs. Surprising validators can change some minds. But dysrationalia stops many minds from changing, and that is caused by cognitive biases (hardware), but also a lack of understanding of probability, logic, and scientific inference (software).

It may be difficult to turn your back on your past beliefs, but according to #69 The Horror, we must always accept that what is done is done, and we, therefore, ought to strive to live well from now on so as not to reach the end of our lives and have only shame and regret to look back upon things that can no longer be changed. This will not be easy. In #75 The Ring of Gyges, we see how our intuitive moral feelings are often in conflict because of the debates that rage within us regarding the self vs. society, or society vs. the environment, or the short-term vs. the long-term, or just the fundamental choices between competition and cooperation. This is what drives the two faces of humankind, but wise people can see this and act accordingly. When we do so, we may truly begin to love life, and even see, as in #20 Condemned to Life, that immortality is not a curse. It is the logical outcome of evolution, and we ought to be able to bear it. Such long good lives, or at least, for now, such a good long succession of them, would indeed be “beautiful.” But what exactly do I mean by that?

My brief reflections – Traditional religious beliefs are mostly nonsense. Moreover, the divine command theory is ridiculous as Plato demonstrated in the Euthyphro, the problem of evil devastating for classical theism, there is no invisible gardener, etc.

I’ve never found much to recommend Kantian deontology, although I think a modified utilitarianism has a lot to offer. Like Mr. Gibney I think that evolutionary ethics explains the origins of ethics and can also function well as a normative ethical theory. I would modify Mr. Gibney’s “good is that which enables the long-term survival of life” by adding “and flourishing of life.” Survival isn’t sufficient by itself for goodness. (Note that Mr. Gibney seems to recognize this later on in the essay.)

I would also modify Mr. Gibney’s “1. Life is. 2. Life wants to survive. 3. Life ought to act to survive.” While I think you can get is from ought I don’t think you can get it quite that easily. (Perhaps Mr. Gibney is just summarizing here.) For example, Schopenhauer would argue that life wanting to survive is just a will to live that perpetuates suffering. So again we must enter the picture and choose to try to survive well, live well, or flourish.

(Next up – the thought experiments dealing with aesthetics.)

My friend Ed Gibney has written on each and every one of the thought experiments in  Julian Baggini’s, The Pig That Wants to Be Eaten: 100 Experiments for the Armchair Philosopher. He has also summarized his own100 blog posts on Baggini’s 100 thought experiments in “What I learned from 100 Philosophy Thought Experiments.”

(Here is his summary of, and commentary on, Baggini’s thought experiments dealing with metaphysics. It follows from a previous post on thought experiments dealing with logic. I have added my own brief reflections at the bottom of the page.)

From Ed Gibney’s blog, reprinted with permission.
http://www.evphil.com/blog/what-i-learned-from-100-philosophy-thought-experiments

3. Metaphysics

Traditional metaphysics seeks to answer the questions: 1) What is there?; and 2) What is it like? On the first question, we see in #90 Something We Know Not What, that there is an impossible barrier to break through at the core of a physicalist worldview, which requires a fundamental assumption to be made in order to act at all.

Then, in #63 No Know, we see that through the eons of the entire age of life, and overall the instances of individual organisms acting within the universe, the ability of life to predict its environment and continue to survive in it has required that ontologically the universe must be singular, objective, and knowable. If it were otherwise, life could not make sense of things and survive here. We may never know if that is TRUE, but so far that knowledge has survived. The objective existence of the universe may indeed be an assumption, but as a starting point, it now seems to be the strongest knowledge we have.

After this first assumption, we can (provisionally) bring into our worldview the entire accepted cosmology of scientific facts from the realms of physics and chemistry and their related offspring. But when we get to all the fields of biology and the social sciences, there are a few more mysteries left to uncover. Namely, the mind-body problem with its concerns about identity, consciousness, free will, artificial intelligence, and the rationality of emotions.

As for identity, #12 Picasso on the Beach shows that everything is ephemeral over long enough time horizons. #11 The Ship Theseus shows that identity is not a fixed, unchanging thing; all borders are fuzzy. In #2 Beam Me Up, we see that I am material, but not only this present material. That is because, according to #65 Soul Power, a full grasp of identity must be multi-level, it must take account of what the self knows as well as what others know, both of which change over time. #88 Total Lack of Recall expands on this by noting that according to Ubuntu philosophy, which has its origins in ancient Africa, a newborn baby is not a person. People are born without ‘ena’, or selfhood, and instead must acquire it through interactions and experiences over time. In John Mbiti’s words: ‘I am because we are, and since we are, therefore I am.’ This helps explain why #46 Amoebaesque shows that none of the four traditional locations of identity — body, brain, memory, or soul — can stand alone to explain who “I” am.

In fact, according to #38 I Am a Brain, our personal identity is some bundle of our purely physical body parts plus our mental parts that reside in our physical brains. As seen in #30 Memories Are Made Of This, the individual self can be regarded as the totality of a set of perceptions within a body. In #54 The Elusive I, it’s even more apparent that we are collections of mental states or events: “bundles of perceptions”, as Hume said. This bundle theory view of the self may take away some personal, religious notion of a lonely, individual, immortal “I”, but in return, it binds us together with all of the rest of life who are in the same boat as “we” are. This is comforting. For #56 The Total Perspective Vortex shows us that we are just another species of animal life on a single planet orbiting one of the 30 sextillion to 30 septillion stars in the universe. We should feel awe when contemplating infinity and extinction, and exposure to both of these concepts does aid our judgment and moral character in choosing actions that comport with the meaning of life.

Can we really choose? Do we have totally free will? Or has everything already been determined by prior physical states? From our subjective perspective, something in the middle makes the most sense. #9 Bigger Brother shows that observer effects lead to unpredictable actions in humans. In #21 Land of the Epiphens, we see how thinking can affect our choices, and so hard determinism is unproven. According to #31 Just So, however, there is nothing outside of our evolutionary history that influences us. And so we arrive, via #25 Buridan’s an Ass, at the conclusion that the chaos of small influences in a changing universe may have been required to cause some decisions, especially in early forms of life, but our evolved freedom to now choose influences from any past action ever known and any possible future ever imagined gives us practically infinite free will now, even if that freedom is ultimately constrained at the limits of what is possible.

Is artificial intelligence something we can include in this realm of possibility? Can we create metaphysical subjectivity in new forms of existence? The limitations of epistemology in a physical universe mean we’ll never know for sure, but according to #39 The Chinese Room, emotions, definitions for good and bad, and the ability to learn to meet a hierarchy of needs are probably enough to create strong artificial intelligence. They are all we have ourselves.

Psychology and all the related sciences of biology can then inform us about the physical basis for these mental things. In #18 Rationality Demands, we see that reasons and feelings are not separate, they influence one another. Further, according to #80 Hearts and Heads, there’s a bi-directional feedback loop between reasons and emotions. These connections aren’t always consciously known or personally understood, but the link is always there. Our job as philosophers is to improve the functioning of this system by improving the logic behind our evaluations so that our emotions motivate us in the right direction. But what then is the “right” direction? To answer that, we must have ethics and definitions for “good” or “bad.”

My Brief reflections – Again so much substantive material here. As for personal identity, I think that Hume’s bundle theory and/or Buddhism’s idea of no-self is about right. Clearly, we just don’t have identity the way most of us imagine; if indeed we have any real self at all. And there almost certainly is no kernel that is us.

As for free will, I’m not sure what Mr. Gibney means by ” practically infinite free will” but I’m skeptical. I’m not a hard determinist, but I think that to say we are genomes in environments is a nearly exhaustive explanation of what we are. Still, we are not rocks, and free choice (which needs to be defined carefully but which is very, very limited) is something that emerged along with consciousness. That is, unlike rocks which are completely determined (let’s forget quantum theory for the moment), we have some deliberative faculties because we are conscious.

As for strong AI, I see no reason whatsoever why consciousness can’t exist on substrates other than our biological brains. In fact, in an infinite universe, consciousness may exist in almost limitless forms.  Finally, I completely agree with Mr. Gibney on the interrelationship between reasons and emotions and that it is a moral imperative to improve our thinking. Quoting from Pascal:

“Let us endeavour then to think well; this is the principle of morality.”

(Next up – the thought experiments dealing with ethics.)

My friend Ed Gibney has written on each and every one of the thought experiments in  Julian Baggini’s, The Pig That Wants to Be Eaten: 100 Experiments for the Armchair Philosopher. He has also summarized his own 100 blog posts on Baggini’s 100 thought experiments in “What I learned from 100 Philosophy Thought Experiments.”

(Here is his summary of, and commentary on, Baggini’s thought experiments dealing with metaphysics. It follows from a previous post on thought experiments dealing with knowledge. I have added my own brief reflections at the bottom of the page.)

From Ed Gibney’s blog, reprinted with permission.
http://www.evphil.com/blog/what-i-learned-from-100-philosophy-thought-experiments

2. Logic

First off, as seen in #42 Take the Money and Run, logic puzzles alone don’t always teach us much. However, #6 Wheel of Fortune helps us see that our guts are bad at statistics. And to solve any paradox, like the one in #70 An Inspector Calls, you must carefully define unclear terms. #64 Nipping the Bud shows that simple answers to complex situations are always wrong in some way. And via #49 The Hole in the Sum of the Parts, it’s a “category mistake” to treat concrete things and abstract ideas as if they both existed as singular entities.

In #85 The Nowhere Man, we see that “meaningless statements” whose meanings seem clear is a contradiction in terms, but this is the kind of problem that was solved in mathematics by the invention of the concept of zero. Just as “the present King of France” or “the round square” don’t refer to anything, neither does the number zero, and so such linguistic oddities might, therefore, be labeled xero, as in, they are neither true nor false, but technically xero.

In another problem for the application of logic, we see in #16 Racing Tortoises that time cannot be slowed to a halt. This then shows us in #94 The Sorites Tax that the concepts of TRUE and FALSE were built on an ancient’s view of the universe as an unchanging and eternal thing. Once we discovered evolution in 1859, and the Big Bang was confirmed by background radiation in the 1960s, our cosmological revolutions should have led to logical revolutions as well. You cannot impose eternal and unchanging TRUE/FALSE logic on an evolving and expanding universe. I call this the Static-Dynamic Problem of philosophy. One can only apply logic to a static picture where TRUE or FALSE definitions can remain valid. Once you move to the dynamic realm, classical logic breaks down.

Nonetheless, as in #61 Mozzarella Moon, when mutually exclusive ideas mingle, they must either adapt or go extinct, and it would be much better for all involved if the changes didn’t have to come from violent conflict (might doesn’t make right), so it’s vital we figure out how to root out truly maladaptive thoughts by using logical reason alone. Sadly, as seen in #24 Squaring the Circle, irrational beliefs in gods are unaffected by rational arguments. And so we, therefore, must move to the subjective realm to understand emotions and other views about the nature of one’s reality.

My Brief Reflections – There is a lot here but I agree that as long as there is time, as long as there is a tomorrow, we cannot claim to know something definitively.  Still, I’d argue that if we can enhance our intelligence, merge with AIs, create a global brain, become transhuman, etc., then there is a possibility of adjudicating our disputes with reason alone.

(Next up – the thought experiments dealing with metaphysics.)

My friend Ed Gibney has written on each and every one of the thought experiments in  Julian Baggini’s, The Pig That Wants to Be Eaten: 100 Experiments for the Armchair Philosopher. Gibney has also summarized his own 100 blog posts on Baggini’s 100 thought experiments in “What I learned from 100 Philosophy Thought Experiments.”

(Here is his summary of, and commentary on, Baggini’s thought experiments dealing with metaphysics. It follows from a previous post on worldviews. I have added my own brief reflections at the bottom of the page.)

From Ed Gibney’s blog, reprinted with permission.
http://www.evphil.com/blog/what-i-learned-from-100-philosophy-thought-experiments

1. Epistemology

What do I know? From #1 The Evil Demon, we cannot be absolutely certain of anything. #62 I Think, Therefore? shows that not even cogito ergo sum is a bedrock. Everything is uncertain and all knowledge is probabilistic. In #41 Getting the Blues, we saw that knowledge comes only via sensory experiences. We haven’t found any exceptions to this. This is reinforced in #13 Black, White, and Red All Over, where the physical nature of the universe creates an epistemic barrier to our knowledge. As a consequence of all this, #63: No Know shows that since we can never be certain that any TRUTH will remain unchanged in a changing universe, our cosmological revolutions need to sink into our epistemological understanding. Knowledge can only ever be: justified, beliefs, that are surviving. For such an evolutionary epistemology, all theories are “true” only provisionally, regardless of the degree of empirical testing they have survived. #73 Being a Bat showed that this evolutionary perspective provides a clear and interlocking set of beliefs that consistently come together to help solve the most fundamental questions of philosophy.

What about the knowledge of others? What do they know? And what can we ever really say to one another? #47 Rabbit! showed that we cannot know for certain that we are talking about the exact same thing whenever we talk to someone, in this language or another. Through #74 Water, Water, Everywhere, we see that the meaning of our words evolves as more information comes in. This is why the many and varied efforts of philosophers of language to find logically perfect and universal definitions of meanings are doomed to failure. There is hope, however. #23 The Beetle In The Box shows that we cannot know what is inside other minds, but our shared evolutionary history makes it highly probable that there is much in common. For example, in #59 The Eyes Have It, vision has shared the same chemical basis across the entire animal kingdom for over a billion years. We can’t Know with a capital K what others see, but it is extremely likely to be the same as what we ourselves perceive. In #19 Bursting the Soap Bubble, our shared evolutionary history shows that we all see the world similarly, but we must still be open to hearing others’ views and change our minds when it is justified. In fact, according to #3 The Indian and the Ice, we absolutely must change our minds, although only when it’s appropriate.

How do we know when it’s appropriate to change our beliefs? In #40 The Rocking-Horse Winner, we see that knowledge cannot be generalized from prior perceptions, nor predicted using the assumption that the universe is uniform. The best we can do is prove through falsification via the scientific method what does not work. In the face of this, #28 The Nightmare Scenario shows that there is a big difference between productive speculation, which is the hallmark of good science, and pernicious speculation that specifically eliminates the possibility of testable hypotheses. As shown by #51 Living in a Vat, there are infinite unfalsifiable notions about reality so none of them are more probable than any other. Therefore, none of them ought to have any bearing on our behavior. In fact, as shown by #81 Sense and Sensibility, if a belief is completely unscientific because it is unfalsifiable, then the burden of proof for such strange ideas must fall on the person advocating the notion, since such things cannot be disproven, and there are infinite such nonsenses (like Bertrand Russell’s teapot orbiting the sun, the flying spaghetti monster, or all historical notions of God).

To reiterate, according to #93 Zombies, we cannot use our general epistemological uncertainty to arrive at any epistemologically certain statements, such as “physicalism is true” or “physicalism is false.” Philosophers seem to enjoy speculating about the unknown and fighting about what may or may not be there while the evidence is gathered by scientists, but none of these merely potential occurrences have any weight whatsoever to actually affect our current knowledge. They are observations with an n of zero.

So now that we have some knowledge—justified, beliefs, that are surviving—what can we do with this?

My brief reflections – I agree with Gibney’s epistemological fallibilism/skepticism modified by the view of the provisional nature of all truth. I would only emphasize that this does not imply relativism, as the provisional truths of science are often supported by mountains of empirical evidence. The best a rational person can do, as Locke and Hume taught us, is proportion their assent to the evidence.

(Next up – the thought experiments dealing with logic.)