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Mind and Medicine Notes HPS 0612
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Date Created: 08/17/15
1715 What is a disease When should a condition count as a disease What kind of conditions should count as mental conditions 0 Example Short stature o Is being abnormally short a disease Maybe a mutation Or maybe your family is just short 0 Example Obesity When it comes to mental disorders Alcoholism a disease Orjust bad behavior weakness of will Compulsive Gambling Homosexuality until 1973 the APA considered homosexuality as a mental illness 0 How can we decide whether homosexuality is or is not a mental disorder 0 Samuel Cartwright a slave owner in precivil war south and he thought that slaves that ran away from their masters were mentally ill he called it drapetomania If you lack normal biological functioning then you have the disease l OBJECTIVIST approach If you make a judgment that someone has a disease then you re making a normative claim or you have a subjective view Normativist Facts vs Values Evaluating vs Describing John shot Smith Describing It was wrong forJohn to shoot Smith Evaluating Contrast between Subiectivist and Objectivist is whether we have to bring in morals or not 0 Value judgment has no affect on disease l objectivist Objectivist Value judgments do not enter in a signi cant way into medical judgments Whether or not we treat something as a disease matters a lot 0 If it s a disease then it s a medical problem and thus the person should be treated medical intervention 0 If it is not regarded as a disease then no treatment is required 0 Insurance 0 With medical disorders if a psychiatrist can nd a medical issue wrong with a person then they can get medical treatment and insurance 0 We tend NOT to hold people responsible for the diseases that they have and NOT responsible for their actions 0 Crimes in our legal system those with behavior resulted from a disease are not held accountable in the same way as those who are considered quothealthyquot When we label a condition are a disease we PATHOLOGIZE it 0 Something is pathological abnormal or deviant about the person The person has a malfunction Authoritarian Regimes People who were political dissidents those who objected to the government were considered mentally ill 0 Such people were placed in mental h Normativist Struck by our willingness to label behavior by a iness because they believe that we clearly thing the behavior is just considered wrong 0 eg the slave owner didn t like the action of saves running away 0 Authorities disapprove of the opinions of the dissidents l so when we label them we objectively say something is wrong with them 0 When we label something as a disease there is a hidden value judgment particularly with mental disorders o eg homosexuality was considered wrong and deviant in the past and labeled a mental illness Thomas Szasz myth of mental illness l Normativist In the case of most mental illness those who supposedly have the illness are behaving in ways that we disapprove and there is no objective condition In the case of mental illness if an identi able mistake could be found in the brain that was connected to the behavior then there could ve been an actual disease l claimed that there is just no physical cause for most mental illnesses Christopher Boorse extreme Objectivist When we label a condition as a disease we ought to mean that the condition is due to a biological malfunction Judgment of harmfulness is distinct from biological malfunction o Notion of malfunction is completely objective biological Eg function of heart is to pump blood if heart is failing is to do so malfunction then you have some form of heart disease Human body is made up of cells tissues organs organ systems 0 At each level biological function could be discussed A disease could be desirable l against normativist view 0 Flat feet got you out of the draft 0 Bipolar Disorder Depression those who are highly creative artists musicians scientists l They suffer from mood swings and they believe that having this condition is a big part as to why they are so creative Conditions that we nd undesirable are not always diseases 0 Having a big nose l undesirable by many 11215 Defenders of normativism appeal to examples like labeling of drapetomania or homosexuality as diseases to motivate their position But Boorse s account provides a rather natural treatment of these cases opposed to judgement of having a disease because it is undesirable this does not mean he thinks a disease is desirable Boorse s view Argument in favor of Boorse There are many conditions we regard as undesirable without thinking of them as disease 0 l being less physically than average but no biological pepsiafunction and hence not legitimately regarded as a disease Issues with Boorse s claim What exactly does biological dysfunction or malfunction mean How can we tell whether such dysfunctions are present Is there always a sharp dividing line 0 l normativist say a dysfunction is a DISGUISE to an undesirable claim Boorse claims that the line bw normal function and malfunction is not just a matter of what is statistically common or average 0 Eg some tooth decay is common universal even But tooth decay still has a biological malfunction Distinguishing between disease and illness 0 Disease is purely biological malfunction o Illness has a further feature that does involve a value judgment in which the condition in question is undesirable A disease is an illness if it o Is undesirable for its bearer o A title to special treatment if what you re suffering from is regarded as a disease than it is covered by insurance 0 A valid excuse for normally criticizable behavior crime in which legal system treats differently or antisocial behavior If something is going to count as a disease 0 l important economical and treatment consequences entitlement to treatment 0 Important legal consequences excusable behavior that is otherwise inexcusable We can identify diseases in plants and in relatively simple animals like fruit ies which re ects the fact that the notion of disease is a biological noUon Species typical means that the organ or structure performs in the way that is designed to perform for members of that species in terms of its contribution o Is it important to point out that when Boorse talks in terms of function and deign does NOT mean that organisms literally have a designer The is rather biologists nd it natural to think of biological systems as if they were designed to achieve certain functions Health as a Theoretical Concept Boorse s Biostatistical theory 0 Health is normal species functioning which is the statistically typical contribution of all organisms parts and processes to the organisms overall goals of survival and reproduction The group to which a contribution is statistically typical What are reference classes 0 They include age and gender 0 We need these because the human species shows a wide variety of functioning what is normal in one group can be abnormal in another 0 Normal for men testosterone levels differ from normal for women 0 What it is to be healthy is not to be normal with respect to ANY references class to be normal with respect to the appropriate reference class only However statistical normality per se is neither necessary not suf cient for heath Eg red hair quite uncommon rare blood type 0 rare eye color all still heakhy The notion of function as healthy and malfunction as unhealthy can not be quotDarwinian tnessquot or pure reproductive success 0 Parents hardly become healthier with each successive child Boorse thinks that acceptable concepts of health and disease must rest on a teleological goal driven conceived biology All parts of the body are built and function so as to allow man to lead a good life and preserve his kind 0 l idea appeals to any early preDarwinism Aristotelian concept of biology Boorse thinks that medicine and physiology are shot through with notions such as normal functionquot Boorse s View the basic notion of a function is of a contribution to a GOAL 0 Goal directedness involves ability to alter behavior or adapt in ways suitable to a goal eg Thermostat adjusting to constantly maintain certain temp The structure of organisms shows a meansend hierarchy with goal directedness at every level Boorse claims whatever goals are chosen function statements will be valuefree since what makes a causal contribution to a biological goal is certainly an empirical matter 0 Most fundamental goal for whole organism is survival and reproduction There are hybrid views of normativism and objectivism l eg Wake eld disease requires BOTH a dysfunction and has to be harmful in some way 1142015 Boorse s Biostatistical Model Continued The subject matter of comparative physiology is a series of quotIDEALquot types of organisms Eg the function of the lens in the ye is to focus light on the retina however this function is not falsi ed by existence of people with cataracts There is enough commonality to talk about an ideal type Idealization l exempt away from various details Idealization is statistical NOT moral or esthetic or normative in any way 0 l so there is a typical species designquot o Is this inconsistent with a Darwinian natural selection Boorse says quotNoquot claiming that the many traits we have in human population are quotdriven to fixation in a population If one design is superior in point of view of tness and ef ciency then eventually it will operate in such a way to be present in everyone in a population Medicine and physiology would be impossible if there way so typical species designquot for humans What about traits that are not universal No one form of polymorphic functional traits eye color blood type is yet xed in the population and can thus be included in the species design DISJUNCTIVELY Some intraspeci c differences can not be handled disjunctively SEX and AGE these involve distinct species design Nlurrnall distributiun cantinu us variati n l 39h I39ll ill of population Frequency E i i l l a a l Phen tye Size Baf n etc Tails of the distribution l areas way out on the ENDS of the distribution Disease corresponds to being on the tails of the distribution l some notion of DYSFUNTION Distance from the mean at which abnormal functioning begins is CONVENTIONALLY chosen What about universal or statistically common diseases eg Gum diseases hypertrophy of prostate in old men and lung irritation are diseases typical of the whole population or sex or age group These are not statistically abnormal in the reference class l whole class is viewed as functioning abnormally Boorse says such cases are so few and no need to worry about them What about atypical distributions In the case in which traits are not distributed normally How do we apply the framework and understand the notion of the distribution of the trait What is abnormal Joseph Margolis On Normativism Opposing view to Boorse Margolis is a normativist about disease He doesn t think that judgments of disease can be grounded in claims about departure from natural biological function RATHER disease and illness are departures from socially grounded NORMS and expectations lllness as a lapse of some sort with respect to given norms of healthquot 0 l clearly a value judgment Healthy states are those we DESIRE and disease states are ones we want to AVOID The human body has changed relatively little over millennia the relevant norms have changed relatively little over time in case of SOMATIC the body not mental medicine We avoid many of the same bodily conditions that the ancient Greeks wanted to avoid Norms concerning health are relatively stable judgments of health and disease are still norm dependent Role of value judgment becomes OBVIOUS when it comes to mental health andiHness 0 Here we see clearly the role of ideology and social goals eg ADD school requires you to sit and listen quietly and not many little kids can do this quite easily especially little boys 0 Back in the day when school wasn t as common a kid that was active and lled with energy wouldn t be seen abnormal 0 There is a switch in social expectations Even in the case of somatic medicine technological changes and changes in social expectation can change our conception of what counts as a disease Eg Suppose a drug was discovered to increase life expectancy then society would begin to ADJUST its expectations o If something can be treated then it is more often than not regarded as a disease and vice versa things not able to be treated are not diseases Caplan would claim here what about untreatable diseasesquot Eg Huntington s is a disease but has NO treatment Margolis thinks this accounts for judgments in cases like sickle cell o If you have one sickle cell allele then you re resistant to Malaria Aa but that doesn t alter that aa is a disease Health and disease judgments seem to involve reference to ideal or normal performance or functioning of bodily systems Are these purely scienti c judgments For Margolis NO 0 For Boorse YES Some problems with normativism Being an alcoholic is generally considered undesirable but it is controversial whether alcoholism is a disease Worry is that normativism cannot EXPLAIN why there is a controversy here 0 According to normativism if it is undesirable then there should be NO question as to whether or not it is a disease but there is a question Naturalisms Boorse s view tries to x this problem by tying the notion of disease to biological dysfunction in order to show alcoholism is a disease you would have to show something more than that it is just undesirable you have to shoe that there is a dysfunction or biological problem 0 The complaint by others here is that Boorse is resting on inadequate BIOLOGY more Aristotle than Darwin 1212015 For Boorse an accident that leads to blindness or loss of a leg is a disease 0 Most people would consider this a disability 0 this brings up the fact that some people don t even believe it s a disability but in fact they just have different abilities How bad is it to have a disability also de nes whether or not it s a disease 0 The same dysfunction in different social contexts l more of less disadvantageous depending on context 0 For Boorse how bad a condition is is the bias of a society 0 Eg In a place with no glasses it s hard to be nearsighted Are harmless dysfunctions still diseases Eg fused toes Boorse would say it is a disease Wake eld dysfunction has to be harmful would say it s nota disease Nonaggressive nonlife threatening tumors or quotcancersquot are they disease 0 Clearly there is a dysfunction but it is not so obvious that it s a disease Szasz The Myth of Mental Illness The Antipsychiatry Movement The antipsychiatry movement Emerged in the 19605 0 Key gures include Szasz RD Laing The Divided Self and Michael Foucault Madness and Civilization Themes 0 1 The speci c de nitions or criteria for hundreds of current psychiatric diagnosis or disorders are vague and arbitrary leaving too much room for opinions and interpretations to meet basic scienti c standards o 2 Prevailing psychiatric treatments are often more damaging than helping to patients 0 3 Patients who are odd different eccentric or unusual orjust have problems living are stigmatized as mentally ill 0 this happens because the notion of mental illness is itself such an unclear and illde ned category RD Lang in particular held that people who we often think as suffering from severe mental illness schizophrenia are simply people who see the world differently and act differently from the rest of us 0 Problems socially rather than individually caused Other key criticism of mainstream psychiatry Inappropriate and overuse of medical concepts and tools to understand the mind and society 0 l miscategorization of normal reactions to extreme situations as psychiatric disorders Overreliance on drugs to treat psychiatric problems facilitated by ties that health professionals have to the pharmaceutical industry 0 l tendency to down play other therapies eg talk therapy 0 Abuse of power and authority relations as when patients are treated and institutionalized AGAINST their will 0 In the 605 this was a lot easier due to fewer legal protections against it Thomas Szasz 19202012 0 Born in Hungary moved to US in 1938 0 Professor of Psychiatry at State University of New York Szasz suggest that mental illness is in roughly the same category as possession by witches or the devil or other supernatural explanations Mentally illness is unexplanatory Saying someone is mentally ill is just as much of an explanation as calling them possessed l gives no information o The notion of illness only makes sense as a biological or physiological phenomenon it implies some notion of abnormal biological functioning l to this extent Szasz agrees with Boorse Much of what we label as mental illness is not associated with clear brain disorder or abnormality or at least if there is an abnormality present people who are labeling know NOTHING about it Szasz doesn t deny that such people have problems but he says it s inappropriate to think of them as ill or sick o l Szasz says they have problems in living 0 All of are subject to problems in living in some degree it is a spectrum and we are ALL on it 1262015 Szasz is particularly opposed to the tendency of some to automatically treat people who behave in morally bad ways as mentally ill 0 Someone who commits a murder should not be automatically regarded as mentally ill the murderer may simply be a bad person Szasz is concerned that as a result of our tendency to medicalize or pathologize behavior that we disapprove of we may stop assessing that behavior morally Language of sickness and illness comes to displace judgments of good and bad Physical illness involve departure from some clearly de ned biological norm or a biological dysfunction 0 These are largely objective matters 0 By contrast when a patient is said to be mentally ill the norm from which he or she departs is typically social or moral and to make this diagnosis of mental illness a more subjective matter l the therapist s OPINION Example a patient who believes that he is Napolean or is being persecuted by communists Szasz claims these are only symptoms of mental illness if the beliefs in question are false Example DSM lV TR used until two years ago symptoms that have to be present in major depression must satisfy any ve of the following criteria Depressed mood Diminished interest 0 Weight gain or loss 0 Insomnia or excessive sleep 0 Fatigue or loss of energy 0 Feeling worthless or guilty Diminished ability to concentrate Recurrent thoughts of suicide l EXCEPTIONS If someone who is grieving up to two months after loss of a loved one does NOT warrant diagnosis of depression 0 If grieving past two months may be able to diagnose depression Questions 0 Why are criteria so arbitrary Why 5 Why not 4 or 6 Why two months for a griever and no more or less Why exception for loss of loved one and not other circumstances 0 Loss ofjob serious injury etc We have basically built into the criteria of suffering from depression a VALUE JUDGEMENT We consider it appropriate or reasonable to grieve for up to two months but no more 0 However now in DSM V the quotgrief exceptionquot has been dropped which just highlights apparent arbitraries of its earlier inclusion There is a certain amount of subjectivity and arbitrariness to such evaluations Concepts of Disease Both in ordinary medical practice and to a signi cant degree in common sense thinking at present about illness we tend to think of diseases in CAUSAL terms Eg Symptoms of cholera are profuse watery diarrhea and vomiting 0 Cause is infection of small intestine by bacterium Understanding the underlying cause is particularly important if you want to intervene to TREAT the disease effectively 0 For this reason it is often thought desirable when possible to classify diseases by their causes Prior to middle of 19th century many diseases were thought of mainly long collections of symptoms or as syndromes it was thought the same disease could have many different causes Classi cation of psychiatric illnesses remains largely syndrome or symptom based l says nothing about underlying cause Little is known about the causes of most mental illnesses Disadvantages of Symptom based classi cation There may be many different underlying diseases that might give rise to such symptoms List of symptoms itself does tell us if there is one or several diseases We don t have any guidance as to how to treat based on symptoms We don t know what should be included in the list of symptoms and what should not be 1292015 Causes and Symptoms should diseases be characterized by their symptoms or underlying causes Symptoms like cough fever etc are often said to be quotNONSPECIFIC they are not uniquely diagnostic of any single disease but are possible symptoms of MANY different diseases Depression originally thought to be just ONE disease Now usually separated into two bipolar and non bipolar on the base of differential reaction to medication 0 Bipolar l moods have VERY high energy and VERY low ls Schizophrenia just one disease Or many different disease that bear to loose resemblance to one another 0 Here we see a potential DISADVANTAGE of distinguishing among diseases whenever they have different causes 0 If there any many types of schizophrenia how do we treat or diagnose them all Aronowitz asks quotwhen does a collection of symptoms become a diseasequot This question really doesn t make sense unless there is an assumption that there is more to a disease than just a collection of symptoms the quotsomething morequot usually involving the idea that disease should be understood in such a way that there is some speci c underlying CAUSE that is responsible for the symptoms Historical controversy has to whether or not disease should be characterized mainly in terms of the presence of certain symptoms or in terms of some underlying causes o eg early 20th century it was debated whether angina should be de ned just as a characteristic pattern of chest pain symptom based 0 eg quotpeptic ulcer diseasequot which earlier in the 20th century might be diagnosed even in the absence of some speci c anatomical abnormality in the stomach or intestine But now diagnosis requires such an abnormality 0 We have functional dyspepsiaquot which is dyspepsia quotwithout the evidence of an organic disease that is likely to explain the symptomsquot Functional dyspepsia affects about 15 of the population in the west 0 Eg Epstein Barr infection originally thought to be due to the EB virus but now relabeled as chronic fatigue syndromequot Since it now covers cases NOT due to EB infection 0 Sometimes perhaps often the historical sequence is that a disease is rst characterized in a purely symptom based way and only later is a speci c case or mechanism discovered for the disease 0 Sometimes it goes in the other direction like with Chronic fatigue syndrome 0 When a disease is characterized by its symptoms then there may be a tendency to think that the condition in question is not a quotrealquot disease 0 So there is tendency to think that CAUSE based characterization is somehow more objective or perhaps more scienti c Characterizations of many mental illnesses are in terms of symptoms rather than underlying causes often deliberately so bc the underlying causes may be unknown 0 This may raise questions as to whether or not they are readiseases Schizophrenia is characterized by positive and negative symptoms 0 Positive having something Eg delusions hallucinations 0 Negative lack of something Eg lack of emotion care to do anything o It is a list of symptoms and does not tell us what the cause or biological dysfunction is DSM is primarily symptom based as a matter of deliberate choice 0 Not much is known about the cause 0 No agreement as to what the underlying cause is o refrigerator momsquot cold emotionless parenting 0 brain infection in utero o excess of dopamine neurotransmitter Operational5m properties or quantities of interest to science should be de ned purely in terms of the operation used to measure or detect them 0 there is nothing more to intelligence than an IQ testquot 0 all there is to schizophrenia is whatever is measured by the various diagnostic criteria for it o If you de ne Schizophrenia this way then one cant raise the question of whether these criteria are good ones for diagnosing it w schizophrenia according to which it is a brain condition that is distinct from and which causes the symptomsquot 0 here one can raise the question of whether various proposed diagnostic criteria are really reliable indications of schizophrenia SO what is the underlying cause of Schizophrenia The brains of schizophrenics seem to be abnormal in MANY different ways and it is not cleat which of these abnormalities are crucial for schizophrenia what if anything they have in common 0 The abnormalities don t seem speci c to the disease 0 But no doubt that something is wrong Recitation Szasz s Argument Premise Diseases genuine illness have physical speci cation Objection dyspepsia doesn t Premise Mental illness doesn t Objection schizophrenia does Conclusion Mental illness is a myth not real Premise Disease is a psychiatric judgment Premise Psychiatric judgments are subjective ethical legal Conclusion Mental illness is subjectiveinvolves ethical and legal norms Bad examples for Szasz argument 0 Schizophrenia Alzheimer s Parkinson s depression Good examples for Sasz argument 0 ADHD Hysteria Mood disorders Anxiety Cognitive selfperception SocioPsychopaths 222015 Many people with schizophrenia have enlarged brain ventricles But what does this mean Is it a cause Or a symptom These abnormalities are not speci c to schizophrenia and are found in people with other disorders 0 Great deal of evidence of comorbidity between schizophrenia and bipolar disorder The Nature of Brain Abnormalities of Schizophreniaquot paper etiopathology cause of schizophrenia remains unknown in spite of a century of investigations of the brain Nosology branch of medicine dealing with classi cation of diseases Parts of the Human Brain frontal lobe 7 1 occipital lobe cerebellum SpihaI cord l Dorsolateral prefrontal cortex area of the frontal lobe that is particularly involved in planning executive functioning and impulsive control 0 Abnormalities in this area of schizophrenia o Decreased blood ow to this area Decreased blood ow to the frontal lobe is a highly touted nding 0 this is not surprising given that they Temporal lobe and hippocampus involved in memory consolidation formation of new longer term memories 0 Reported that this is frequently disrupted Lateral temporal neocortical areas also seat primary auditory and auditory association cortex 0 Again unsurprising that these are abnormal in schizophrenia since many have auditory illusions They are unable to recognize their inner thoughts and think it is from an exterior source Schizophrenics often seem to have enlarged ventricles that may press on neighboring tissues 0 However these abnormalities are NOT speci c to schizophrenia and it is unclear as to which are merely symptoms and which re ect underlying causes Another abnormality the role of dopamine Excess dopamine theory of schizophrenia l dopamine hormone involved with 0 Disturbed and hyperactive dopaminergic signal transduction 0 Those on cocaine seemed to act like schizophrenics 0 Drugs that suppress dopamine levels seemed to lower schizophrenia symptoms Although much more is known now than 50 years ago and there seems to be little doubt that various sorts of brain dysfunctions are present in this disease underlying causes are still unknown 0 One cant diagnose schizophrenia just by looking at the brain images or by measuring neurotransmitter levels 0 In this sense diagnosis is till symptom based rather than based on any sort of deep causal understanding Mental Illness is Indeed a Myth Packard Plato s metaphor of cutting nature at the joints o Carving meat at the joints instead of trying to go through the middle of the bone 0 In science we need to nd the right way of carving up nature into categories 0 If we don t have the right descriptors as starting points then we won t get anywhere 0 Copper oxygen these are often described as natural kindsquot 0 quotstuff that is greenquot these seem arbitrary or less natural categories or kinds 0 The underlying nature or essence of copper would be that copper is an element with the atomic number 29 o Underlying nature is harder to nd but it explains why copper is shiny ls mental illness the natural kind o Is there a hidden nature of the illness in question that we may discover through scienti c exploration When something is a natural kind then when you know the kind to which it belongs you can predict a lot of its other properties 0 If you learn that one sample possesses a property than you can generalize that other samples also possess that property Natural kinds tend to have determinant boundaries 0 Something either IS or IS NOT copper Take Home Message One may similarly asks whether various categories or classi cations correspond to natural kinds and which do not 0 This is a question one can ask about various proposed disease categories 0 Disease will have various obvious symptoms and as expected are underlying causes 0 Eg symptoms of cholera include vomiting diarrhea but the underlying nature is that involves infection by the bacterium Vibrio Cholera But what about presently sued categories classi cations of mental iHnesses Are these or do they correspond to natural kinds eg personality disorders speci cally cluster B don t have any single underlying nature or cause in common we have a bunch of people who are selfcentered inconsiderate etc but don t have much in common beyond that 0 Maybe something similar is even true for schizophrenia Hillary Putnam s example Twin Earth and XYZ On twin earth there is liquid substance in large bodies around planet clear odorless inhabitants drink it without it you die of thirst l has all super cial characteristics of WATER on our earth 0 But is has a chemical composition of XYZ 0 Should we think of this XYZ as water or not Super cially it is just like water but has different chemical makeup This illustrates that water is not determined by its super cial characteristics but rather by its underlying nature or essence 142015 Suppose we discover brain lesion which is reliably correlated with schizophrenia as characterized by its symptoms 0 we come to regard this as lesion as the underlying nature or essence of schizophrenia Then we encounter someone who has the lesion but none of the symptoms of schizophrenia Does this person have schizophrenia Packard says Yes 0 I say NO l we are guided by super cial characteristics Packard concludes Hence Szasz s claim that mental illness considered as an overarching or generic category is a myth Packard thinks the notion of disease is too complicated and we don t have to de ne it Bypass de ning disease and not worry schizophrenia is a disease or not but ask if schizophrenia is a valid scienti c category According to Packard there is evidence for skepticism with whether or not it is a valid scienti c category 0 Evidence dif culty distinguishing it from other mental illnesses eg bipolar and the presence of minor psychotic symptoms in the general population Underlying causes or nature of schizophrenia are facts about genes or brain structure Genetics some symptoms seem to be heritable but other symptoms are not 0 Having a relative diagnosed with schizophrenia increases your probability of such a diagnosis but it is also clear from twin and adoption studies that environment matters quite a bit too Reliability of schizophrenia diagnosis 0 Reliability how much agreement among different clinicians in diagnosis or among different diagnostic procedures Exclusion rules and comorbidity Piakard describes this as quotgerrymanderingquot manipulate the boundaries so as to favor one class Exclusion rules used to insure uniqueness of diagnosis that would not otherwise occur 0 Eg you cannot be diagnosed with schizophrenia if you meet the criteria for major depression or mania Statistical studies seem to indicate a continuum between schizophrenia and bipolar disorder 0 Scores do not cluster around two distinct poles Psychotic symptoms in the general and prodrome population 0 Claim that as many as 25 od the general population may suffer from transient hallucinations or delusions Prodromal patients who show some symptoms but it is not FULL BLOWN schizophrenia l SUGGESTS CONTINUUM Packard suggests that taken together this evidence suggests that schizophrenia doesn t carve the world at its joints 0 Currently it is characterized by super cial properties 0 But the symptoms are certainly real and no reason to doubt that they CAN be scienti cally explained Evidence that schizophrenia divides into three clusters 0 Positive symptoms hallucinations and delusions Negative symptoms apathy athymia and asociality Cognitive disorganization disturbed speech and problems with attention Cluster B personality disorders narcissistic histrionic borderline and antisocial These often look like they involve moral failings or character defects Packard agrees with Szasz that the Cluster B PDs do involve among other traits failures of virtue and characterquot 0 However it is possible to construct scienti c explanation of the development of virtue and character of how it progresses or fails Are PDs a scienti cally valid kind of category Scienti cally valid means 0 With this PDs are scienti cally valid because knowing that a person is borderline allows one to offer explanations and make inductive inferences Packard believes the Best account of the development of the virtues and the formation of character is Aristotle He emphasizes the development of the good person over time The acquisition of virtue and character is a long process 0 Three stages 0 Good upbringing and habituation of virtue Virtues establish as habits long before children become re ective about them 0 Child being guided in such a way that in acquiring these habits he or she is able to come to see they are good One comes to get pleasure out of acting virtuously 0 Acquiring knowledge of why virtue is good This requires reason and re ection and will occur when child is older 292015 Nicholas cage and the damage of his orbital frontal cortex which completely changed his personality before and after the accident 0 Indicates the importance of the orbital frontal cortex What underlies development of PD traits Consider the intense anger and impulsivity which is characteristic of borderline PD This likely involves problems in functioning of Orbital Frontal Cortex which is involved in impulse control management of emotional responses and recognition of emotions in others 0 Study with comparing borderline PD patients with patients with damage to their orbital frontal cortex concludes that both were very similar 0 Suggest that anger and impulsivity characteristics of BPD can be explained with abnormal development of the orbitofrontal cortex because of early childhood neglect and abuse So whether or not PD s are natural kinds Pickard thinks they re not the failings of virtue and character typical of them can be scienti cally explained In other words Szasz can be right in that there is an ethical dimension to PBS Some questions raised by Pickard Are mental illnesses quotnatural kindsquot 0 Are physical illnesses quotnatural kindsquot 0 Suppose at least some mental illnesses are not natural kinds reason Pickard described then how should they be understood or treated Is it appropriate to think that PDs are failures of virtue and character 0 Should we try to keep any kind of moral or normative evaluation out of psychiatric thinking and diagnosis even indirectly Wachbroit quotNormailty as a biological Conceptquot Normality is a crucial concept in understanding biological function and in medicine and physiology but nor part of physics 0 Marks crucial way of how biology and medicine is different than chemistry or physics 0 Also arguable that reference to normality required to characterize what a disease is Wachbroit distinguished three different concepts of normality 1 Normality as a statistical concept as given by mean mode median of a distribution 0 what about diseases most of the population has l gum disease 0 2 Normality as an evaluative concept as when one talks of cultural or ethical norms 3 Normality as a biological concept as in talk of a normal heart a normal reaction a normal environment 0 Wachbroit claims this statement is not about any particular heart Nor about all hearts since some fail According to Wachbroit you cannot use the notion of function to explain the notion of normality Rather the talk of function presupposes a notion of biological normality In order words biological normality is the more basic concept Theories of function Talk of function is pervasive in biology and medicine and on central issue is to understand what the notion of biological notion of function involves One common theory of function is the quotgoalquot of the system theory 0 Function of heart is to circulate blood Organisms has a system in which blood is circulating Therefore heart is present Not a valid argument because it doesn t show that the heart is NECESSARY because Nagel claims that although an organisms can have circulating blood without a heart this not be a normal organismquot 0 Thus argument works if we restrict our self to biologically normal organisms Another theory of function etiological theory 0 Another class of theories of what a biological function is are ethological theodesquot C Says that the function of something is that particular effect or consequence which explains WHY is it there 0 Thus the heart is there quotbecausequot of its ability to circulate blood 0 In case of biological function this because is typically there in terms of natural selection 0 This is why we think of it as having function of pumping blood 0 Problem is that malfunctions as well as functions can have evolutionary explanations Sicklecell anemia is an illustration of this point 0 Results from point mutation in the gene that produces hemoglobin Think of it as A form that doesn t produce sickling and a associated with sickling Having the a reduced the ability of your blood to carry oxygen 0 However everyone has two alleles of this gene one form each parent Offspring can be AA Aa heterozygous or aa depending on which allele they get from each parent 0 Heterozygote superiority in some areas of world 0 If you have Aa the oxygen carrying capacity of your blood is reduced somewhat with AA but not so much as to be deleterious 0 Moreover it confers a much greater IMMUNITY to malaria in comparison with AA 0 In an area with lots of malaria being Aa confers a selective advantage 0 If you have aa the oxygen capacity of your hemoglobin is severely compromised so much that this condition can be fatal This is sickle ca anemia This is a case of heterozygote advantage with the heterozygote being tter than each of the homozygotes in areas in which malaria is endemic ln area of malaria AA is not so t and neither is aa 0 If tness preservation is Aa is strong enough then both aees will be present in the population Wachbroit writes that an ethoogica theory have to conclude that the hemoglobin resulting from the sickle cell gene performs a function Even though it may confer a bene t sometimes it is still a malfunction The bene cial effects are seen as functions 0 The deleterious effects are seen as malfunctions l he concludes that etiological theories of function need to appeal to considerations of normality in order to capture the function Malfunction distinction we need to 0 make distinction between traits that are products of evolution and confer bene ts 0 and traits that are products of evolution that are non bene cial Wachbroit thinks that the notion of normality is central to biology and distinguishes it from physics and chemistry Normality plays an important role in biological especially physiological explanations Some general observations about evolution You might think that since what would be best for the species is that sickle cell shoud entirely disappear evolution should produce this outcome 0 Evolution is subject to CONSTRAINTS in this case Mendel s laws which characterize reproduction in sexual organisms 0 There is always a chance that some offspring will be aa it cannot be avoided Even if natural selection is operating very ef ciently aa will not be eliminated from the population Is it okay to think of natural selection as optimization but remember there are constraints Natural selection does not always eliminate variation from populations or drive traits to xation Even though Aa is the ttest in areas of malaria natural selection cannot produce a population that consists ofJUST that genotype Operation of natural selection 0 1 Variation in some phonotypica trait in population 0 2 Variation must be heritable 3 Variation must be responsible for tness differences The initial source of variation is random in the sense that is not correlated with the needs of the organisms Variation is produced by mutation or by other processes involved in gene replication 0 Variation is not directed it IS blind Natural selection is a tinkerer it works with the materials it has available Often these are constrained in ways that prevent natural selection from nding the solution that might seem most optimal in the abstract Natural selection does not look ahead in the sense that it necessarily nds global optima At best it nds local optima Fitness liq 5 i I i IE 39 t 39l 1 H IQ quot39 u u H Ina v AI R H 1 i a39quot 39 H 39 H l r iquot Milanquot WET d H tjllv J Elfin a r f q I 1 HI I u lii an f A r quotAIquotgt u quot I In A Ja gf39a r p 4 an 1212771 c kg 339 39quotn39IQJIJ EVEquotFl Susimm Space Tallest peak global optimum others are local optimum No reason to think that the current design of our species is necessarily optimal from the engineering point of view 2162015 It is not always true that natural selection operates in such a way that it produces a single unique design that is shared by all or almost all and which is in sense quotoptimalquot Instead there are many variations that can be considered equally optimal However natural selection will eliminate some variations that are highly deleterious in terms of tness from the population but not ALL variation will be eliminated Amundsen against normal functions opposite of Wachbroit Social critics claim that the terms normalabnormal carry ideological baggage l describing individuals or groups as abnormal is seen as marginalizing them by use of a falsely objective criterion 0 l Amundsen agrees Amundsen is handicapped in some way himself Amundsen analogizes the concept of abnormality to the concept of race in biology 0 Until recently people took the category of race to re ect important biological differences among different human groups 0 Racial differences don t correlate very closely with other biologically interesting differences Indeed there is much more variation within races than between them 0 No clear cut boundaries between races o All humans as far as we know come from the same relatively small ancestral population 0 Race is not a natural kind because we are not carving nature at its jointsquot Amundsen claims that like the concept of race the concept of normality has NO biological basis 0 Diversity of function is a fact of biology o l abnormal organisms are in fact reaching a functional goal in a DIFFERENT way eg disabled is actually differently abledquot Recall distinction between Naturalists and Normativists Naturalists Boorse and Wachbroi t Notions like normal vs abnormal or function vs malfunction can be grounded in biology Normativists Margolis and Amundsen Deny this They BOTH however agree that certain concepts in the past were ideologically tainted The difference is that naturalists believe that such taint can be avoided by CAREFUL science and normativists DO NOT Amundsen focuses on permanent and stable conditions commonly called disabilities rather than in the more episodic or life threatening conditions commonly called diseases 0 SO question is do those who have quotdisabilitiesquot have a biological abnormality Amundsen is going to challenge the concept of biological normality itself Normativists in general do not do this they challenge the de nition of disease in terms of biological normality Recall Boorse s bio statistical account of disease 1 reference class l natural class of organisms of same sex or age 2 Normal function Statistically typical contribution Amundsen says Variation among individuals in a species can be seen as arising from TWO sources 0 1 Genetic variation 0 2 Developmental plasticity traits an organism develops during its lifetime due to in uences other than its genome A gene doesn t contain a rigid code rather they contain conditional instructions 0 ln environment with such and such circumstance leads to this response There is thus a tension between Boorse s and Wachbroits ideas about there being a relatively determinant species design that is normal and shared by most members 0 f the species and on the other hand evolutionary theory which going back to Darwinian emphasizes variability within naturally occurring populations 0 According to Amundsen Darwin did NOT think that there was a single typical species type with deviations from normality Amundson thinks it is wrong to think tat typical species design speci ed by genetic blueprint which can then be used to specify departures from what is normal Slipjer s goat as an illustration 0 In 1940s the biologist EJ Slipjer studied a goat that was born without forelegs The goat learned to walk bipedal on two legs Goat had many other skeletal and muscular abnormalities but each of these was adaptively suited for life as a biped o This illustrates the inadequacy of the metaphor of the genetic blueprint 2182015 Amundson continued As long as you achieve a function the mode and means of receiving it do not matter Hydrocephaly example Can lead to profound physical and mental disorders by the backup of cerebrospinal uid causes the ventricles of the brain to balloon many times its snze Resulting pressure leads to enlargement of cranium andor reduction in volume of the brain tissue l Ventricle lls 95 of cranium and leads to profound disability 0 but half of this severely affected group has le over 100 functionality can also be retained even with major loss of cortex volume I even those with loss of an entire hemisphere can gain full function Organism may perform some activity in a different way in a different modequot than is usual but perform it at the same level of functionality as others use of sign language as an example of this Eg sign language as illustrations of behavioral plasticity 0 Sign languages used within deaf community are themselves natural human languages they are not pidgins and sign langauge full structural complexity and expressive powers of speaking In summary the goaldirected processes of biological development are not nely tuned towards the production of functionally identical species members What is taken to be good or healthy in an evaluative sense with the statistically unusual also be regarded as indicative of an illness or bad health 0 A rejects this Says that being statistically unusual is consistent with being functional through some alternative mode perhaps 0 quotThe healthillness and normalabnormal dichotomies are illusionsquot 0 very strong claim Amundson think that the notion of a xed secies design with determinate limits on functional potential stills plays a DOMINANT role in disccsuons of health and care ethics 0 Views against Amundson 0 Norman Daniels the preservation and restoration of normal functionquot is a primary goal of health care Amundson thinks that quality of life should be measured subjectively by satisfaction and ful llment by those living those lives 0 Physicians however estimate the quality of life of disabled people are much lower than the patients themselves think it is o A common explanation for this is that functionally abnormal people who report a high quality of life have lower expectations than functionally normal people Amundson rejects this and says that this condescendation is similar to racism 0 He says that the disadvantage that is attached to blindness and paralysis derives not from the ATYPICALITY of one s biology but from the absence of appropriate tools in the environment Caplan ls aging a disease Direct response by most is that s crazy aging is natural and inevitablequot Most also accept that as people age they are more likely to develop certain diseases Caplan asks s aging independently of the above particular diseases a disease Many think that aging is natural and thus should not be regarded as disease 0 However many conditions in aging people are natural in the sense that virtually everyone gets them and they are regarded as disease 0 l hypertension malignant neoplasm etc 0 So why are these regarded as disease and why isn t aging Caplan asks If we think disease as a pathological or morbid change in the body why doesn t aging qualify o Is aging a dysfunction Or the failure of normal functioning What is aging In one sense it just involves the passage of chronological time 0 When physicians talk of aging they have in mind a particular set of biological changes that occur as patients get older l chromosomal aberrations collage bers become less exible immune system weakens loss of strength and muscle tone etc Talk of aging as natural cant just mean that is it universal and inevitable because there are many conditions we regard as diseases which are also universal and basically inevitable So what is meant by natural then 0 Often in medicine natural is associated with what is seen as a designed function of a bodily system 0 Aging is degisned to serve but what is its function Aging s function Common idea is that aging has the function of removing the aged from the population so that more resources are available for the young 0 Natural selection has designed things in such a way of aging However natural selection quotselectsquot those individuals who have traits that maximize their chances of reproductive success but natural selection does not act for the bene t of species 0 l natural selection will not select for this outcome 0 To show that natural selection selects for aging in individuals you would have to show that aging somehow bene ts the individuals 22315 The sound of the heart beat is just a byproduct of the heart pumping and doesn t really have a purpose The human head at birth is very large at child birth l the reason is that having big heads means big brain 0 A big head also has deleterious consequences l decreases mortality rate of mother 0 Evolution trade off large head good mother death bad bad the good outweighs the bad Complications in childbirth are not the function of large head but a harmful byproduct Caplan says we should think of aging in a similar way l there is no biological function for it but it is instead a byproduct Different explanations for aging reinforce the similarities between aging and other diseases 1 cross linkages in proteins and nucleic acid molecules leading to accumulation of free radicals 2 accumulation of mutations and chromosomal abnormalities 3 increase in number of autoimmune reactions over time There are some general criteria that are relevant to whether something is a disease 1 condition that produces discomfort or suffering 2 condition can be traced back to a specific cause 3 there is a set of clear cut structural changes that follow a regular sequence after the initiating cause 4 set of clinical symptoms or manifestations 5 impairment of function note that not ALL diseases will satisfy any or all of these criteria 0 but in trying to show something is a disease these are the criteria to which people generally appeal Caplan says quotgainingquot satis es all the criteria Objections to aging as a disease First Objection calling aging a disease is pointless since medicine does not know how to treat it or avoid it Response many presently untreatable conditions are still regarded as disease eg Huntington s chorea Second objection tremendous economic and social costs to calling aging a disease Response this is completely irrelevant to whether a condition should be regarded as disease Many conditions carry very large costs of treatment or melioration but are still regarded as disease think of many cancer treatments dialysis institutionalization of mentally ill and retarded This value judgment should be kept separate form whether aging is a disease 322015 Kendler A psychiatric geneticist interested in genetic foundations of genetic iHnesses Levels of Explanation Variables and causal factors are naturally thought of as occurring at different levels or scales eg molecules genes proteins cells organs organisms and social environment 0 We often face choices about which levels are best or most APPROPRIATE for framing causal explanations Statistical mechanics vs thermodynamics as an example 0 Similarly for disease including mental illnesses should we explain at level of genes and neurotransmitters Or some other level one that emphasizes social factors Ethiological causal vs Symptom based Classi cation Kendler is interested in classi cation but to do this one needs to nd the right level or levels at which to characterize the causes of various illnesses this is more easily done for some illness than others 0 Some illnesses seem to be better behaved in terms of affording possibilities for satisfying causal explanations than others 0 Some diseases seem to have causal explanations that score highly on our criteria for good explanations and where the causes seem simple and to occur at the same level 0 In such cases an etiological approach works well 0 Other diseases particularly mental illness are NOT like this 0 l they seem to have many different causes occurring at many different levels and the causes in question don t seem to be satisfactory explanations 0 here the etiological approach seems less satisfactory because the causal situation is so complex and messy Hard medical Model 0 Each disease has a single type of cause which we can use to de ne or characterize the disease In question 0 Cause is taken to be straight forwardly biological According to Kendler this works for SOME disease but not for others speci cally many mental illnesses 0 We need to abandon this model for mental illness but not the search for a cause 0 Hard medical model works best when applied to disorders that have a single clear cause 0 Paradigms diseases resulting from Mendalian genetic defects vitamin de ciencies and infectious or parasitic diseases 0 Question is are all diseases like this Kendler argues NO most diseases especially mental illnesses have no hard medical singular cause Risk Factors 0 A factor that raises probability of disease o It can mean a correlation or a cause but usually a correlation o eg being young is a risk factor to measles not a cause Criteria for good explanations and for the right level of explanation Strength how strongly is the candidate explanatory variable associated with effect in this case disease or disease risk 0 Various ways of measuring this correlation coef cient quoteffect sizequot statistic used in biomedicine such as an odds ratio risk ratio or the proportion of variance accounted for Causal Role degree to which alleged cause truly alters the probability of disease as opposed to being associated with it through non causal Mechanisms quotcorrelation does not mean causationquot Eg if you smoke a lot you are likely to have yellow ngers and develop lung cancer correlation Real problem for genetic causes of diseases 0 Very common for researchers to discover gene for a disease only to withdrawal claim because it s really a correlation Manipulability degree to which i the identi ed cause or risk can be manipulated that is experimentally altered at least in principlequot and the degree to which such interventions alter risk of the disease 0 Very important in clinical settings Generalizability degree to which causal claim holds across a range of different systems or background conditions Eg variant of a gene that leads to bad ability to metabolize alcohol only found in east Asia Speci city degree to which that explanation applies only to the disorder under consideration versus other disorders Whether a causal relation leY is speci c depends on whether has lots of other effect besides Y Proximity location of candidiate cause in the casual chain to the disease Idea is that some causes are closer more proximate to disease than others WXYZdisease Z is a proximal cause and W is distal Generativity re ects the probability that the variables identi ed would be able Kender proposes to illustrate and test these criteria s Example where criteria are fairly well satis ed Cystic Fibrosis CF arises from mutations in the protein CF transmembrane conductance regulator gene CFTR This cause is generalizable mutation causes CS in any environmental background cause is speci c does not cause other kinds of disorders CFTR mutations are proximate to the disease mechanism since they directly initiate the pathophysiological cascade leading to the illness Example of Alcohol Dependence AD 0 What is known about the genetic risk factors 0 Estimated heritability is 5060 established by identical twin studies 0 But these aggregate risk factors are not highly speci c because they are associated with a broad risk of abusing drugs and disposition to externalizing behaviors aggressive behavior conduct disorder l these genetic factors affect much else besides AD 0 These are also speci c genes that are known to have speci c molecular effects 0 Eg genetic variant that inactivates enzyme which is involved in metabolism of ethanol 0 Very common in east Asian populations and is strongly protective for AD Dysfunctional neural systems are another risk factor for AD 0 These aren t speci c though 0 There are also personality traits that predispose AD 0 Very nonspeci c an increase risk for many other psychiatric problems and they are also not very manipulable we don t know how to manipulate personality traits very well 0 Social risk factors such as parental loss poor parentchild relationships child sexual abuse environmental factors 0 Very nonspeci c and very distal Also unclear that they will be very generative Kendler thinks that a similar pattern as in AD will emerge for many other mental illness such as major depression Mechanisms Causes and Explanations How should one go about explaining things anyway in the biomedical sciences Central idea in the 2021th century philosophy of science that science often aims to provide explanations rather than to merely describe 0 But what is involved in providing scienti c explanation The DeductiveNomological DN Model of Explanation Paradigm exposition Carl Hemple Two concepts of the DN Model 1 Nomological component fancy word for quotlawquot 2 Deductive component According tot the DN model an adequate scienti c explanation takes the form of a deductive argument Fact to be explained the expanandum is deduced or derived from a set of premises the explanans The explanans must contain at least one law as an essential premise the premises in the explanans must be true and the explanans must deductively imply the explanandum Laws other premises l fact to be explained Eg Newton s derivation of planetary trajectories from his laws of motion and his law of universal gravitation What is a quotlawquot Big problem in philosophy of science Philosophers think of laws as universal and exceptionless generalizations This means such generalization hold everywhere and always without EXCEPTION or at least it is though that the aim of science is to nd such laws Many criticisms of DN model One is that it does not seem to t the biological sciences and medicine very well because they contain very few laws There are many true generalizations in biomedicine but often these do not have the features associated with laws Many biological generalization have exceptions and don t seem to hold universally think of mendel s laws which are not really laws as philosophers think of laws genes close together on a chromosome don t assort independently Biological generalizations seem much more local in scope than paradigmatic laws hold a best for terrestrial organisms or a certain subclass of these Think of the genetic code and the Central Dogma of Molecular Biology 0 DNA l RNA Protein 0 Same in every organisms and one directional NOT TRUE Virus reverse transcriptase Doesn t hold universally Conclusion drawn by many is that even if the DN model ts physics fairly well it does not t the biomedical sciences very well 0 Something else is needed Thinking About Mechanisms an attempt to replace the DN model with something which better ts the biomedical sciences key idea is that in the biomedical sciences scientists usually or typically explain by providing info about mechanisms and this is very different from providing a DN type explanation Mechanistic explanation don t work by appealing to laws 0 What is a mechanism as biologists understand this notion Key ideas in MDC Analysis in terms of two concepts entities and activities Entities are the things that make up the mechanism and activities are what those things do 0 Eg DNA molecule neuron protein neurotransmitters are entities Activities include binding etc MDC s account of mechanisms Mechanisms are entities and activities organized such that they are productive of regular changes from start or setup to nish or termination conditions 0 Eg mechanism of chemical neurotransmission MDC think that if you can describe these intervening steps in such a way that there are no gaps then one has traced a productive continuity from the start step to the nish step 0 This makes what is going on seem intelligible o Eg ingestion of aspirin to relief of headache the chain that leads to relief how does it happen exactly Decomposotion and Localization 0 Typically mechanistic explanation involve decomposing systems into parts or components which behave in certain ways and exhibiting how the behavior of the whole system results from behavior of that part ReducUon For this reason mechianistic explanation are often reductive whole systems is explained in terms of smaller more microscopic parts and principles governing these 0 Contrast with a more holistic or systems level approach General question Do all explanations in biomedicine have to be mechanistic MDC seems to suggest yes or at least that more mechanistic explanations are always better explanations What is MDC view of functions 0 Functions are the roles played by entities and activities in a mechanism To see an activity as a function is to see it as a component in some mechanism that is to see it in a text that is taken to be important vital or otherwise signi cant Notion is malfunction broken normal and is the derivative from or parasitic on some understanding of normal function Nevri paper Nevri rather than thinking of malfunction or pathology as a breakdown of normal function he ants to talk about pathological mechanisms in their own right 0 There are two kinds of mechanisms normal physiological mechanism and pathological mechanisms 0 A pathological mechanism is not just a normal mechanisms that is broken in some way but a distinct kind of mechanisms that is deserving of its own theoretical study 0 Rather than trying to understand disease in terms of disruption of normal function we should try and understand it in terms 0 Leads to a notion of a real pathological mechanism and understanding how it works 0 Eg diabetes insipidus 3162015 Physiological mechanisms Outcome invariability Limited by a variational range Homogeneity Pathological mechanisms Outcome variability In uenced by regulating factor with no range constraint Ambivalence Unlike physiological mechanisms pathological mechanisms are not productive of regular mechanistic progressions and vary with external and internal factors Pathological mechanisms may result in a wide array of outcomes ranging from complete recovery to death Sara Moghaddam Taaheri T understanding pathology in the context of physiological mechanisms We should view pathology as a mater of brokennormal malfunctioning mechanisms rather than having to do with pathological mechanismsquot in their own right what Nevri advocates All the features that Nevri ascribes to pathological mechanisms can be seen as broken physiological mechanisms MT argues that different outcomes depend on which part of the mechanisms is broken so if we specify what is broken and background conditions there will be a unique outcome Broken normal view is also more therapeutically usefu If we separate pathology into discrete theoretical mechanisms it becomes hard to have a concrete de nition of disease when the two are separated When the mechanism of disease is known the progression of disease can be viewed as the effect of a broken normal stage or series of broken normal stages in the overall normal or physiological mechanism Genetic diseases What does it mean to call a disease genetic Natural answer the disease is caused by one or more of organisms genes But what does this mean Magnus doesn t worry about nding the quotrightquot de nition of genetic but a more useful approach to try to understand the properties of different de nitions and to think about which would be best to satisfy the de nition What is causation suppose two quantities are correlated l you can predict the value of one from information about the value of another CORRELATION does NOT equal CAUSATION Statistics Mean Variance Standard Deviation Covariance correlation coef cient Rquot2 extent to which one quantity can be estimated accurately What is the different between cause and correlation Smoking example Y whether you have yellow teeth L whether you have lung cancer S whether you smoke We don t think that Y causes L but there is a third factor S involved that causes both thus there is a correlation between Y and L NOT a causation 3182015 Fisher s theory that smoking was not a direct cause of lung cancer but there was a gene that disposed someone to smoking and that gene also disposed someone to lung cancer He was smoke himsel
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