How sure you need to be depends on what you’re doing (Or: As usual I think social media discussions are missing a more fundamental disagreement, this time about a SCOTUS nominee)

Brett Kavanaugh is being considered for a position on the Supreme Court of the United States. He’s also been accused of sexual assault. This information has been all over social media lately, and there seems to be, as there often is, a fundamental disagreement behind the arguments. On the surface, we see basic support versus opposition of the man. There are some straightforward statements of believe in Kavanaugh or else the women who have accused him, mostly prominently including Dr. Christine Ford. There is also quite the range of more general claims. For instance, some people are saying that you should always believe someone accusing someone of sexual assault. Others are taking the opportunity to speak up about what they take to be a worrying trend of false accusations. But these generalities are harder to grasp, so let’s look at the particular case at hand.

In this particular case, besides the basic disagreement about facts, there’s a prior disagreement about how sure either way you need to be to claim to believe in one side or the other. Or, more straightforwardly, to take one side or the other. What actions or consequences are at stake on a belief one way or the other change how easily we’ll take a side or make a belief claim.

A common way philosophers model sure-ness is by using what are called “credence levels,” numbers between zero and one that represent how confident one is in the truth of a statement.  I’m probably 99% sure it’s not going to snow in Phoenix tomorrow morning. Maybe even more sure than that. So I have a credence level of .99 for that. I think I have three decks of cards in my closet, but I’m not super sure. I wouldn’t even bet on even odds. My credence level is maybe .3.

These credence levels are also nifty for expressing how sure of something to be to act a certain way. For instance, in the US, a guilty verdict requires “proof of guilt beyond a reasonable doubt.” This is often expressed as requiring a credence level for the guilt of .99 or higher. But in a civil case, the standard is just believing the verdict is more likely than not. That is, .51 or higher. You can pick all kinds of cases. If you really hate rain, then maybe you only need a .1 credence level that it’ll rain tomorrow to bring an umbrella.

But before you can pick a requisite credence level in a given belief for a given action, some sort of goal is required. Or multiple goals. We have competing values that push us in either direction. I don’t want to get all wet walking to work, but I also don’t want to needlessly carry around an umbrella. I don’t care that much about staying dry, but carrying an extra umbrella annoys me a fair bit. So I need probably a .9 credence level that it’s going to rain. We want to have a functioning justice system, but we really don’t want to punish the innocent. Better a hundred guilty people go free than one innocent person get locked up. So we need that credence level of .99.

The difference in rhetoric of Kavanaugh’s supporters and detractors is revealing of entirely different focuses. The opposition is generally mostly focused on keeping a rapist out of the Supreme Court. For that end, you don’t seem to need to be all that sure. You might even, as I do, flip the proof of guilt beyond a reasonable doubt around to proof of innocence beyond a reasonable doubt. The cost of being wrong is much higher if he’s guilty. Meanwhile even if he’s innocent, a replacement can easily be found. Given the plethora of options and importance of the position, we should be really, really sure that we get someone really, really good. If there’s any reason at all to suspect a Supreme court nominee is a rapist, then we should just move on to the next option. So my opposition to Kavanaugh in this regard only requires a credence level higher than .01 for his guilt. (It is in fact higher than that, though I haven’t spent a lot of time fine-tuning my position. The credence level is far enough above .01 that not much farther thought is needed.)

On the other side, Kavanaugh’s supporters focus on a few things. Shouting “innocent until proven guilty” is one route, suggesting a demand for a .99 credence level for his guilt being needed to deny him the job. But digging a bit into it, there’s more of a focus on some notion of justice. The actual consequences are secondary to the importance of doing the right thing. This would move the bar probably at least to .51. Either Kavanaugh is deserving of the position or he is undeserving, but that fact has nothing to do with the actual results of him getting it. The question comes more down to “Is he a good guy?” as a quasi-factual question about his character.

Some do appeal to some notion of “ruining his life” being a bad thing, to which the standard response is that not being on the Supreme Court does not constitute one’s life being ruined. The standard response to that is that his reputation is being destroyed. I’d be really surprised if anyone hinged their judgement of him on how the Senate votes. The damage, deserved or not, is done. But this does bring up the presence of various actions to take or beliefs to have based on the credence level of a single statement. For example, while I only need a .01 credence level that someone is a rapist to say that they shouldn’t be a major government official, I do still think .99 is morally required to incarcerate someone. Given the former is the context usually at hand, .01 is the bar used to determine what to say I believe. In most of our lives, we have other contexts. If a friend shared a story about having been assaulted, my role would be to comfort, be confided in, or something along those lines. So the bar is pretty low for me to believe. Even if the evidence I have would seem a little suspicious, I don’t need to be very sure at all. On the other hand, if someone I don’t know accused a close friend, I’d probably need more convincing. (It’s a bit harder to pin this case down, though. I have plenty of evidence already built up leading me to believe that my friend wouldn’t do such a thing. So maybe I wouldn’t need that high a credence level in my friend’s guilt, but I would need a lot of evidence to get the credence level even to a medium level.)

These middle cases suggest to me that there’s some reasonable room for needing different amounts of convincing given different conditions. Whether you’re seeking to find someone good enough for a Supreme Court position, send someone to prison, support a friend, or achieve some notion of justice will determine how sure you need to be to take one position rather than the other. And how sure you need to be can vary from one extreme to the other. Given this fact, perhaps the prior questions need a bit more attention. We have the facts as they’ve been presented. Throwing them back and forth appears to be rather unconvincing. But maybe the sureness levels can be moved. If I think about it, I’m not super sure that .01 is the right bar to deny someone a spot on the Supreme Court. I could probably be convinced that I need to be more or less sure. Some people may also be able to be convinced on what the important values at hand are. This is often the route I take. I don’t think that I can convince people to believe Ford if they don’t already. I do think that I can convince a few people that the bar for being on the Supreme Court ought to be really high and so even if you think that Kavanaugh is probably innocent, you should still support moving on to someone who isn’t even accused.

There’s some back and forth from there. Usually the first defense is that a really corrupt political group might just get people to block everyone Trump appoints. I have responses to it, mostly appealing to the growing incredulity and subsequent increased scrutiny. But the point is that the badness of a rapist on the Court is much harder to deny, the badness is much harder to counterbalance, and even rather strong supporters of Kavanaugh are likely to have some non-zero level of suspicion. So this is the argument to have. It has another nice feature, too: The open acknowledgement of different contexts and aims requiring different levels of credence allows us to be more clearly supportive of people who have been assaulted and are in the current discussion being made afraid of coming forward for fear of widespread disbelief. It also satisfies some of the worries about the potency of false accusations. Sexual assault, among other crimes against others, is unfortunately often very difficult to be super sure either way what happened. But, we do at least have a fair bit of middle ground to work with. You need to be pretty damn sure someone did something wrong to lock them up. You don’t need to be so sure to just not give them a bunch of power. And you don’t need to be so sure to give someone some support when they’ve been hurt.

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Defence Against Conspiracy Theories Undermining All of Our Beliefs

I somewhat recently relearned the importance of a lot of work in epistemology (philosophy of knowledge). Sometimes arguing another round about skepticism can feel divorced from the world. But there are in fact plenty of skeptics running around causing trouble. They pose questions about, well pretty much everything, especially including the sources of our knowledge themselves. Now, as I have mentioned, I am not a skeptic, and I think there are plenty of ways to defeat skepticism, but in this post I’d like to dive directly into the epistemic problems.

Trusting People Who Know Things

One of the most common angles of attack for conspiracy theorists is our sources of knowledge. In particular, who we trust to get information from. We do get most of our knowledge via hearing or reading what someone else said. Most science you learn in school is the teacher and the textbook telling you some facts. You don’t look at it for yourself. Religion, too, is filled with relying on other people to know things and pass them on. And the news is literally just people telling you things that you don’t have the time to go see for yourself.

So we clearly rely on other people telling us things. And if you were to rank the ways you come to know things, via sensing them, remembering them, inferring them, hearing them from others, etc., you probably put hearing them from others low on the list. At least in American culture, trusting your own senses, memory, and conclusion-drawing skills before trusting someone else to know seems to be the norm. So when a conspiracy theorist looking to spread his ways points out how much of what we know is based on taking others’ words for it, the realization can be jarring.

So, sure, if you ask about how we know science stuff, or a lot of other stuff, then sure, 99% of us have to take it on people’s word. Experiments are time-consuming and expensive. However, as you might have noticed, we do manage to do stuff. Veering off the question of knowledge for a second, someone at the store could start throwing stuff instead of shopping. People on roads could ignore the lines. And back on the question of knowledge,  a news reporter could spontaneously just start saying knowing lies. And in fact, on rare occasion, these things do happen. But usually they don’t. That we manage to make stuff work, even if not with 100% certainty, is interesting in itself. Especially given language and knowledge are both themselves socially-created.

One could dive deep into the social sciences asking what it is that makes people honest, but they are. Sure, some people are dishonest or think they know when they don’t know, but sometimes you think you know when you don’t. Your memories can be wrong even if they feel right. Your senses can deceive you. Faulty reasoning is common. Yet the solution is not to throw these out. It’s to recognize that 100% certainty is not the right bar to use. And just as you realize that totally distrusting your senses isn’t going to work, you should realize that totally distrusting other people isn’t going to work. So how do you judge when someone is to be distrusted? Well, more on that in a bit, but basically, you already know how. When someone has a track record of lying or being wrong, you become suspicious. When someone has a track record of being honest and correct, you trust even some of their more unlikely-sounding statements.

Making Sense

Another popular avenue for conspiracy theorists to start asking how things make sense. Money is just pieces of paper or numbers in a machine. Laws are just words on a page. How do all of these clearly human-made symbols have any power in the world at all? Nothing makes sense!

Well, again, a dive into the social sciences, particularly sociology and social psychology, would be rather instructive. But we can get a lot of mileage out of asking what you mean by “make sense”?

First, let’s look at the usual cases of making sense. It’s a way of describing behavior. Someone walks to work, and that makes sense. Someone puts some merchandise on the checkout counter at the store, and that makes sense. You see someone tapping at her phone, and, again, that makes sense.

Now let’s look at what doesn’t make sense. If you’re walking down the sidewalk and see someone rolling on the ground, that doesn’t make sense. What do we mean by “that doesn’t make sense”? We mean that you can’t explain the behavior. When people do stuff we try to tell a story about it. Preferably some sort of story that guides us in our actions. We need to know which way he is rolling so we don’t collide. We might consider that the rolling man is on fire, and if we make sense of the rolling that way, we’ll be looking out for fire hazards. Maybe he’s going downhill and it’s just for fun. Maybe he’s mentally disturbed. Regardless, we try to piece together a picture of the world. This picture enables us to act.

We can look back to science. Given everything falls, we all include gravity in our pictures . We do this to make sense of things falling. Part of trusting people is making sense of their saying things as an attempt to communicate the information that they are saying.

Doubting Doubt

Let us now go on the offensive. If you just doubt everything, then you won’t get very far. I don’t mean this in some abstract sense, but in a very commonsense way. If you doubt your senses all the time, you won’t have much input about the world. If I want to go make myself a bowl of rice right now, I have to trust my senses are right about the floor, door, bowl, rice, and so on. And as I walk away from the rice cooker, I have to trust my memory of turning it on, lest I end up in an endless cycle of checking it. Oh, and my knowledge that the rice cooker cooks rice. And that rice is a food. The list goes on and on. Could my roommate have poisoned my rice supply? I suppose that is a possibility. But it doesn’t make any sense.

But, again, onto the offensive. These theorists all too often fail to doubt whether they should be doubting. If I’m walking and come to a rickety bridge over a deep chasm, sure, I’ll doubt it. This doubt is expressed by testing it. Step on the bridge with one foot on secure ground. Maybe shake it a bit. But a busy sidewalk? I’m not going to doubt whether it will fall out under me. That would be insane. If someone jumped on each sidewalk square three times to be sure it’s safe, we would say they have severe OCD.

There are many, many things we simply don’t doubt. And we don’t doubt them because we have no reason to doubt them. Doubting everything sounds attractive as a slogan, but it’s wildly impractical. Even someone reading this and objecting probably trusted up until this point that I’m writing in English with words meaning what they usually mean. I would implore someone who didn’t to object, but he didn’t understand what I said anyway and won’t get the message.

Purpose

So, what’s the point of all this knowledge stuff? Conspiracy theorists point to the different and competing claims of science, reason, faith, religion, and maybe some others. Usually this is for the sake of  undermining our understanding of purpose. They are convinced that the people telling us about science or religion or whatever else has an agenda. Those educators want us to do their bidding, and we need to think for ourselves to find the real purpose of action, whatever it may be. So now we can carve up the questions constructed by these theorists into two:

  1. What is a good source of knowledge?
  2. What is a good reason to do something?

And we need both in the most general sense. There’s a worry about falling into traps of outright outlandish and foolish doubts. But at the same time we still have to be wary of believing too easily.

Now a dive into epistemology (philosophy of knowledge). There’s (basically) two very general notions of how to think of knowledge and it is justified, so to speak. One way is like towers. You have some basic, ground-level beliefs or knowledge. You build up from there. And if you pull out the bottom, then the whole thing collapses. This is the idea people seem to commonly have going into this discussion. So a conspiracy theorist comes along and makes you question your ground-level beliefs. You have the problem of not knowing which things are good foundations. Because knowing which things are good is itself knowledge!

The other way is more like a web. There are some more or less important parts, but nothing is truly at the bottom. You throw new stuff at it. Some can fit in. Some will be rejected. If you tell me Nixon was just re-elected president, I’ll have some real reservations because other parts of my web do not fit at all with that. Nixon is dead, and the US doesn’t usually have elections in the middle of a term and overnight. But if you told me the rice I started earlier is done, that seems pretty plausible. The best explanation my web can figure for someone telling me that is that my rice is done.

So, let’s assume that the web is the better model. Epistemological foundationalists are free to object in the comments, and actively encouraged to do so if they can also provide the same defense I do here:

As a person in the middle of life, you already have a web. Your web is working well enough. Sometimes you’re wrong, but you get around being correct often enough to not be put in a psychiatric ward for having crippling hallucinations and delusions. Now think about your good enough web. Sometimes you come across new information. Say, you hear a knock at the door. New info. It comes to the web. Using other stuff you know, you figure the knock probably happened, and it probably means that there’s a person there. So you get up and look. And then you answer the door, whatever. Good web.

Now, let’s say it was the wind. So you answer, and nobody is there. That’s more info. So that goes to the web, and you cut out the previous belief that someone was at the door. Maybe you come up with an explanation, such as that it was the wind. This gives us some idea what it is for you to believe or know something. The something that you believe is part of a web that leads you to create new beliefs and act in ways that are useful to you.

Then we have the question of which sources of knowledge are right or trustworthy. So ask, well, why do you trust your ears? Probably because thus far they usually lead you the right way. And today we have convenient examples of stuff leading the wrong way. Lots of people ignore the feeling of vibration on their leg because the phantom phone vibrations lied enough that they cut out of their webs as a good source of info. So, as in the first section, you can ask this of people, too. As I promised, we are returning to the question of how to know who to trust.

Do you know someone who lies a lot? Do you trust what she says? No. Why? Because you’ve found that the things that she says always ends up having to be cut out of the web. Likewise, what is it to trust someone besides to take the information they present as good enough for inclusion in the web? It doesn’t have to be the most strongly connected to the web. If a close friend tells you something important, you’ll probably be very hesitant to cut it out of your web. But if someone at the store tells you chips are in aisle three and you don’t see them, then you assume the dude was wrong and move along. The fact that people can misremember aisle numbers is part of your well-functioning web.

Doubting Everything

Okay, so individual threats to the web can be handled, but what if you’re worried about your whole web being wrong? What if actually an evil demon is feeding your mind with perceptions that are nothing more than the demon fucking around? What if you’ve been so thoroughly misled, as some of the more extreme conspiracy theorists might contend, that really you need to throw everything out and start over?

First, remember now, what does it mean when you say or think “This is wrong?” It means that the alleged information (“this”) cannot fit into your web. You might not be 100% certain that it shouldn’t, but we’ve established that that’s fine. So something is coming to your web and not sticking because it just doesn’t fit. Then to think “Everything I think is wrong” is to think that your whole web does not fit with your web. This means that the very idea of doubting everything is incoherent. You can check if pieces of the web fit with the rest of the web. You cannot check if the whole web (at once) fits with the rest of the web. There is no “rest of the web” to check against.

Now, of course, the web might still feel a bit loose. But now the way to tighten it and make it feel coherent can be made clearer. Because it’s now clear that each piece can only be tested individually, and that you already have a web, you can look at the more troublesome pieces and explicitly put them to the test. And then like how when you put one foot on a rickety bridge to assure you’re self that it’s safe, you have shaken the belief in question and found that it does hold together.

Putting the Web into Action

There are yet factors that give us good reason to suspect large swaths of web. For instance, your socioeconomic status makes you oblivious to a lot of things. Geography will highlight some things and hide others. And there’s just plain ignorance. I know I don’t know much about botany, so the whole region of my web dealing in plants is kinda shady.

Nonetheless, there are parts of the web that come up because we have to act, and maybe we have to believe. But we don’t have to believe very strongly. So, for example, I’ve been made aware, through various means, that I have obviously white skin and features, and as such, there are important things that I’m just going to miss. I can’t know what it’s like to be black. I know that, though, so that goes in the web. And when something looks like it wants to be part of my web when I know it should not (because it’s something I know that I can’t know), then the web rejects it.

Now, are there probably some deeply wrong parts of the web? That is, parts that will not stand up to scrutiny? Well, maybe. But there are at least two kinds:

  1. Something that will affect my actions in an important way.
  2. Something that will not affect my actions in an important way.

The whole reason for caring about this stuff is because of actions, right? Knowing for knowing’s sake is dandy, but the reason we get really  worried  is because of the beliefs that affect how we act. So toss out category 2.

This leaves category 1. Given the values you have and situations you’re likely to encounter, you can look around the beliefs in the relevant areas of your web and test them. Maybe you know you need more info, so you can find some to help build up that area of the web.  Many situations that some knowledge will be useful for can be foreseen. Of course, sometimes you can’t or won’t, and actions have consequences. That’s a large part of why we care about them. If there’s bad consequences, then that goes to the web, and you can figure out what went wrong. You learn from mistakes and whatnot.
So then maybe a new worry comes up: What if you make a really bad mistake?
Well, you already know what counts as really bad, right? Maybe the kinda bad stuff is fuzzy, but the really bad stuff is clear. And being really bad, you can reasonably make general rules of action that steer you clear of it. Like, killing the wrong person would be really bad, so you make a general rule to not kill anyone.

 

 

 

 

 

Idealists are not climate change deniers

I find Berkeley to be an odd choice of foil in this article.

The author introduces Berkeleian idealism, then poses the problem of a common reality (through Johnson). This, as far as I know, isn’t a super big problem for Berkeley. In fact, it seems to strengthen the case for God’s presence, which is a major part of his metaphysics.

Of course, the atheist idealists have a bigger challenge in answering this objection, but I’ve yet to see it ignored.

Then he moves to an idea that seems more along the lines of what Derrida or Lyotard (or at least my admittedly weak understanding of them) would say — that we all have own own experiences or narratives and cannot break past that. I.e. there’s only the narrative of each subject. Someone agreeing with them would probably disagree with him. I’m not sure someone following Berkeley’s ideas would.

(I also find this point, which seems to be the crux of the argument, uncompelling:

“That’s why we do all agree that sick children denied health care suffer, that opioids are addictive, that adults need jobs to put food on their tables. ”

1. We don’t all agree on any of those.

2. In that sentence, and each other, there’s a tacit “In my experience,” which is just the heart of the matter. Perhaps in his experience everyone agrees. In my experience they do not. Hooray for situations in which no rule of judgement can apply to all subjects involved!)

WP: Twin Pain

From the writing-prompt-s tumblr:

You live in an alternate world where twins — fraternal and identical — can feel each other’s physical pain. You are an only child with no siblings. One day, suddenly, you feel a burning pain in your chest.

This prompt brings up a few problems. The first is of identity: what makes a pain yours? The next is an epistemic problem brought up by tumblr user askmissbernadette:

It’s called heartburn, learn to eat slower you hooligans

In a case where you may or may not have a long-lost twin, under what circumstances can you figure out whether or not you do? And if you can figure out that you do, how can you figure out that you can?

Identity

Let’s set aside your circumstances in the prompt and only consider the more usual case in this world of a pair of twins who feel each other’s physical pain. To feel someone else’s pain can take a variety of forms, particularly when the limitations of reality are lifted. Five levels are apparent:

  1. On the tamest end we have real-world recognition-based empathy. For example, if you see someone hurt, you recognize the hurt and are hurt in recognition of their pain.
  2. Next, also from the real-world, we have the sort of empathy where in response to seeing someone else having a feeling, you feel something mirroring that feeling. Of course, this is based on your perception of the feeling.
  3. A non-real level, when someone else feels a pain and it causes you to feel a pain through some mechanism. Maybe it’s magic. Maybe it’s really weird laws of physics. Perhaps a device that records their pain, sends a radio signal to a device
  4. A further non-real level, most easily explained by example. Say Ally and Bella are twins in the WP world. Ally gets hit by a hammer in her stomach and feels a pain in her stomach. At the same time, Bella feels a pain with all of the same properties in her own stomach.
  5. On the farthest level, we have the same pain in Ally and Bella. That is, Bella doesn’t feel the pain in her stomach — she feels the pain in Ally’s stomach. Within this type, she may have her own experience of the pain or, somehow, there is only one experience, though they both experience it.

Whether there are actually two options in 5 is itself another question, though. Is there more to pain than just the experience? The options are either there is some abstract entity of pain that is instantiated in the experiences, and thus one pain can be experienced multiple times or by multiple people or else there is only the experience. Perhaps, though, experiences can be repeated, within or across people. If, however, every experience is unique, then one pain can only be instantiated in two experiences if it’s itself some separate thing.

Are experiences unique? I argue they are. Our experiences do not come in neat, discrete parts, but rather messy wholes. When I see the glass on my desk, I don’t just see the glass. I’m seeing a bunch of things while feeling and hearing and smelling other things. Even with regard to the glass itself, it has a certain focus in my vision at a certain distance, and, most fleetingly, at a certain time. Moreover, I recognize it as a glass because of a certain cultural context. Rather than just seeing a clear cylinder with some color in it, I recognize it as a thing to pick up and drink from if I’m thirsty. My experience of it right now is as something not to drink from at this moment, but probably in a few minutes. Likewise, each pain and every other experience comes with a complex context that cannot be repeated.

If there are abstract entities, perhaps pain is one of them. In this case, if Ally gets hit in the stomach, the stomach pain entity is called upon to spawn itself in Ally. The same stomach pain entity is also called upon to spawn itself in Bella.

If instead pain is just the experience, we get the odd case of Ally getting hit in the stomach and Bella feeling that same pain. Here the difference from 4 is most evident. If 4 is the case, then Bella would feel pain in her own stomach. If 5 is the case, then Bella feels pain in Ally‘s stomach since the experience is of a pain in Ally’s stomach.

Of course, the prompt has you feeling pain in your own chest, so if 5 is the identity involved, you have no reason to suspect you have a twin. If 4 is, then we have to ask how the properties transfer. The most evident property of pain is its ouchiness. That is, pain feels painful. But if Ally feels a pain in her chest that’s six inches from her right side but also in her heart, but Bella’ heart is eight inches from her right side, does she feel the pain six inches from her right side or in her heart?

Epistemology of Pain-Twins

Let’s assume the fourth level is the one involved here, and you feel a pain in your chest. Can you figure out if a twin explains the pain, and if not, can you figure out if you have a long-lost twin?

As askmissbernadette brings up, you might just have heartburn. Now, this assumes you have that kind of pain. Even if you’re not familiar with heartburn, you can probably imagine a difference between simple heartburn and being shot in the chest. Likewise, you can imagine a difference between heartburn and being poked in the chest. If the pain is heartburn-like, odds are probably better you have heartburn than you have a long-lost twin, especially if you haven’t noticed unexplained pains up until this point in your life. If not, maybe there’s something. If you happen to have access to doctors and medical tests, that can further your knowledge of the odds either way. If some known, not-super-rare explanation can explain the pain, it’s again probably more likely that than a mystery twin. If not, you might have some reason to be suspect, though the point remains if you’ve made it more than ten years without noticing anything off, you’re probably fine.

This epistemic point undermines the prompt a bit. Little kids get hurt a lot. Unless they’re living unusually safe lives, they run into things, fall, scrape their knees, and generally exploit how quickly they heal. But if you’re nine years old and start feeling a bleeding pain in your knee while sitting in class or feel like you just ran into a wall while watching television, that’s when you’re going to figure it out.

Say your twin and you both managed to avert this. Can you find each other given the pain sharing? If I were that curious, I’d stab myself with a pen in Morse code to send a message. What if my twin isn’t in a context to understand Morse code? Well, some form of rudimentary message sending might be possible. Making obvious intentional pains would draw attention, if there are such things. Doing something like bashing your arm into a tree would generally be unambiguous enough. Getting a responding pain would be a pretty solid clue, though the question would remain why nothing was noticeable earlier.

Perhaps they were in a very long coma (this is fiction, after all) and after over a decade (or more) have finally woken up. Chest pain may be the first pain they experience upon waking up. Unless they immediately back into a coma, though, they will experience more pains. So while the chest pain alone will not put you on good grounding to conclude you have a twin, the series of pains thereafter that do not match your activities will.