Scientific Reasoning Flashcards
Deductive arugments
Valid/unvalid pertains to the sturcture of the arugment
sound/unsound pertains to the truth+structure
Abductive
Infernece to the best explanation
Sherlock homes
Inductive
Not truth-preserving: The truth of the premises does not guarantee truth of the conclusion
* Degrees of strength: The premises support the conclusion to varying degrees
* Ampliative: The content of the conclusion goes beyond the content of the premise
All observed swans are white
therefore all swans are white
Deduction
Truth-preserving: If the
premises are true, the
conclusion must be true
* All-or-nothing: A deduction is either valid or invalid
* Nonampliative: All the content of the conclusion is (implicitly) already in the premise
Hume’s problem of induction
If the world is uniform, then induction is justified
The world is uniform
∴ Induction is a justified inference method
Problem is that it seems like the world i uniform only can be come to by induciton itself and therefore cannot be used to explain itself
Interpretation of probabilties: Frequency Interpretation
the probability of an attribute A in a finite reference
class B is the relative frequency of actual occurrences
of A within B
Benefit: epistemologically accessible
Problem: how do we interpret individual cases
Interpretation of probabilties: The Subjective Interpretation
De Morgan: “By degree of probability, we really mean,
or ought to mean, degree of belief” (1847, 172)
Benefit: no need to search for the ontology of probability
Problem: Can’t people be wrong? If you think one thing
and I think another, isn’t at least one of us wrong? And if
so, what is the standard of wrongness?
Interpretation of probabilties: Classical Interpretation of Probability
probabilities in the
absence of any evidence, or in the presence of symmetrically
balanced evidence. The guiding idea is that in such
circumstances, probability is shared equally among all the
possible outcomes, so that the classical probability of an event
is simply the fraction of the total number of possibilities in
which the event occurs. It seems especially well suited to those
games of chance that by their very design create such
circumstances — for example, the classical probability of a fair
die landing with an even number showing up is 3/6. It is often
presupposed (usually tacitly) in textbook probability puzzles.
Benefit: epistemologically accessible (just need to do
the math)
Problem: We talk of chance outside of games of chance.
The chance of seeing a tree fall down today seems like a
real quantity, but is not part of an equal distribution of
possible outcomes.
Interpretations of probability: The Logical Interpretation
Logical theories of probability retain the classical interpretation’s idea that probabilities can be determined a priori by an examination of the space of possibilities. However, they generalize it in two important ways: the possibilities may be assigned unequal weights, and probabilities can be computed whatever the evidence may be, symmetrically balanced or not.
Benefit: improvement over classical probabilities
Problem: Are chances really about evidence or are they not dispositions regardless of evidence?
Predicitive non equivalence natural selection and creationism
Organisms have flawed adaptatations
H and intelegient designer creates perfect adaptations
H’ natural selection created flawed adaptations
P(H|O) is low
P(H’|O) is higher
interpretations of probability: The Propensity Interpretation
propensity interpretations regard probabilities as objective properties of entities in the real world. Probability is thought of as a physical propensity, or disposition, or tendency of a given type of physical situation to yield an outcome of a certain kind, or to yield a long run relative frequency of such an outcome.
Benefit: Probability is connected to causation
Problem: What is the ontology of a propensity
