HPS250H1F - Logical Positivism - LECTURE 5.doc

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University of Toronto St. George
History and Philosophy of Science and Technology
Hakob Barseghyan

Send to: [email protected] Austrian-English →Popper Carnap - solved same way as Kant (both empirical):  Observational statements (~individual experiences) →only singular ones can be absolutely certain  Theory-ladenness:  Answer depends on accepted theory:  Aristotelian physics (theory)  Newtonian physics  Relativistic (contemporary) physics theory  Object moving continually in curved-space time  Diagnosis: what we experience→depends on accepted theories  Example: neuron synapse (dendrite+axon terminal)  We “slice” our world by means of our theories (intuitively)  We’re all innately inclined towards classifying our surroundings, by means of conclusions based on previous experiences  Theory-ladenness--Naming:  Anglophone naming customs  →perceiving a series of Spanish names as first, middle, last-- at face value → an expert would know the second name is actually used as a surname, conventionally→only an expert would know; one without experiential knowledge of this would be unaware and make wrong inferences  Theory-ladenness—colours:  Scenario 1: my range of perception consists of only 6 colours  Scenario 2: range of perception = 12 colours  Scenario 3: range of perception = greyscale  Theory-ladenness—instruments:  Moon overvation using telescope, spies “mountains”  Conclusion made = There are mountains on the moon  →question: is this pure statement of fact?  We’d never trust proposition of we did not assume trustworthiness of telescope →properly calibrated, adequate materials  We would not, with similar surety, trust this proposition with another, less-perceived-as-accurate instrument  Conclusive theory: we can accept the results of telescopic observations only if we trust our optics  We can intuitively spot circular-reasoning and discriminate against their integration into our own system of accepted concepts  Eory-ladenness:unaided eye  Proposition: there is an apple in front of me  Question: statement of fact?  We do not always trust sensations→only in very specific conditions (i.e. Proper illumination, sobriety, etc.)  If this were not true, we-as a species- would not survive  Therefore, we only trust sensations under certain conditions (even if 95% of time)→ sensations only trustworthy if we conclude in trustworthiness of our physiology  Theory-ladenness: Terms  Another aspect: any statement (inductive) requires concepts (terms). Use of language founds itself on use of concepts.  E.g. This statement uses several terms: “There is a cup of hot tea in front of me.”  Def tea: beverage prepared by adding tea leaves+hot water→this definition founs itself on use of other terms (and thus concepts)→hot water, beverage, tea leaves→further break down to more presupposed underlying concepts (and therefore terms)  Therefore, every statement founds itself on presupposed theories→there are no pure statements of fact.  Two aspects--theory-ladenness:  When making obesrvation/experiment→rely on theories describing workings of employed instruments  What we experience depends on theories we accept→not just external objects  These two aspects ==>Theory-Ladenness (every statement is “laden” in a theory”--theories are presupposed, which are never certain, according to logical positivism, but only probable/improbable)  =any proposition describing experience presupposes many different theoretical propositions. There are no pure statements of fact  *Language→any system of symbols  Does theory-ladenness refer to descriptions of our perceptions, but also the further down to perceptions themselves Question of positivists: if theories not absolutely certin, how possible for observational statements to be absolutely certain? →observations depend on our imperfect theories... So what is our conclusion? →conclusion: they cannot be absolutely certain! Everything is disprovable.  E.g. Instruments→objects→dependent on perceived trustworthiness of instruments  Since theories cannot be absolutely certain...no observational proposition can effectively be absolutely certain either. Probabilism: What killed logical positivists (singular propositions are infallible-- individual experiences are absolute)? →Theory ladenness Another shaky theory—probabilism Supplies feed of “updated probabilities” → increase/decrease in increments (kind of like stock market) Problem of Refutations: Examples: 2 statements— 1. 17% smokers develop lung cancer, and 2. All smokers develop lung cancer (17% probability) They appear equivalent, but are not—first proposition sums up statistics, but nothing more. Second prop—theoretical, and purely false Example 2: 3. 10% children born left-handed 4. All children born left-handed First is a statistical observation; second is hypothetical theory that is false. Probability vs. History of Science—another problem with approach: E.g. The next discovered planet will revolve in an ellipse →why do we accept this? → b/c we believe all planets revolve in ellipses. Why? →Carnap: it has high probability based on past experience →all known planets revolve in ellipses →makes it see
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