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Critical Thinking. At this time I admit nothing that is not necessarily true. I am therefore precisely nothing but a thinking thing Descartes. Reason. O ur explanations have to fit together as a coherent system . We need solid evidence for our conclusions . Good
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Critical Thinking At this time I admit nothing that is not necessarily true. I am therefore precisely nothing but a thinking thing Descartes
Reason • Our explanations have to fit together as a coherent system. We need solid evidence for our conclusions • Good • Solid judgment- Time and effort • Objective- No bias • Solid logic- No fallacies • Bad • Relay on emotion • Rely on authority • Rely on superstition • Rely on assumptions • Rely on misdirection
Reasoning is a process • What is your standard for knowledge? • How much evidence is needed to prove? • When do you change our beliefs? • What type of evidence? • Poor decisions • NOT absent of thinking • Flawed or incomplete thinking • Biases unchecked (leaning to one side) • Emotion (driving our conclusion) • Incomplete (distracted by other things)
Logic • Rules to reasoning correctly • Breaking down arguments • Finding premises (evidence) • Conclusion (product) • Set up of an argument • Correct follow • Is there an inference (connection) • Being aware of mistakes • Long held beliefs
Logic--everyday • Allows to formulate a process to problem solving • Knowing the step to the/a solution • We try to avoid variables And randomness • Try to repeated process • Writing essays • Customer service • Balancing life
Inductive arguments Probable inference The conclusion is the best one that can be drawn from the premises given. Get evidence to argue • Evidence points us to conclusion • Set up is the scientific method • Arguments are evaluated on strength
Deductive arguments • Conclusive inference The conclusion is the only one that can be drawn from the premises given. • Set up with Validity • Statements evaluated with Truthfulness • Arguments are evaluated on Soundness
Validity • Successful argument • Proposition (set of premises) and conclusion have valid relationship (inference) • Does not apply to premises (evidence) • Argument is either valid or invalid • Argument can be valid but not true • Set up right or wrong • Inference becomes central to arguments
Truth • True and false apply to the premises • Is the statement true or false? • Do not apply to whole argument • Premise, statements, are either true or false
Truth and validity Validargument, false premises All Dogs are cats.All Cats are birds.Therefore, dogs are birds. Invalid argument, false premise Cats are birds.Dogs are birds.Therefore, dogs are cats.
DescartesDeductive Logic • Nothing empirically can prove that I necessarilyexists? (never wrong) • I can’t trust my senses? • I could be crazy? • I could be dreaming? • A malicious demon alien controls my mind?
Descartes's Cogito Cogito (I think) Leads to (Therefore) Ergo, sum (I am) Thinking Necessarily proves I exist The conclusion (I exist) MUSTfollow from the premise (I think)
Evaluating Descartes’ Argument: • Dualistic World: He hasn’t proven the existence of his body, just his mind. • Has he proven that you exist, as a thinking thing? • A proof has to be objective, but Descartes’ proof is subjective. • Seems to be opposed to science
Skepticism Reason Evidence Skeptic • NOT negative • Asking for evidence • I accept/assume nothing without evidence/proof • ….gathering data to formulate and test naturalistic explanations… [Skeptic Manifesto]
Issues Outrageous • Aliens & UFOs • Bigfoot • ESP • Government poisoning water • Orwell's Big Brother More of dilemma • Interstellar life forms • Developing organisms • Influential thinking • Vaccinations • Tapping phones and keeping database of phone calls of everyone