Critical Thinking in Learning Biology Human thinking

Critical Thinking in Learning Biology

Human thinking ? • Human beings have a great capacity to hold irrational ideas and arrive at incorrect conclusions. • Thinking does not always lead us to the correct conclusion

Human thinking • Our capacity to be wrong and our proneness to being misled can have catastrophic consequences • • • Not just restricted to science! Hoaxers / scammers Charlatans / pseudoscience Politicians Marketing & sales Commercial claims • The capacity for these areas to delude us is greatly reduced if we practice the principles of critical thinking about claims and arguments.

Examples of recent public debates that require clear, rational thought and have suffered from a complete lack. • vaccines & autism • global climate change • evolution Some bad arguments are easy to spot…

The Question is… What counts as real knowledge and how do we know? How do we make sense of the world? Many sources of knowledge claim to be ‘factual’ – thus containing ‘truth’. Who do we believe? We need a way to evaluate factual claims to determine if they are likely to be true.

The problem is…. . • Our brains act like scientists generating hypotheses all the time • Common sense notions are persuasive and are based on intuition, anecdotal assumptions, habits of thought. • Science questions and challenges “common sense” by analysing the facts in objectively.

Example: Gambler’s Fallacy: • Imagine the following sequence of outcomes: red, red, • With so many reds occurring…it must come up black anytime now!!!!. . . right? • WRONG!!!!!! • Each spin is independent of what happened before. On each spin red and black have an equal probability.

So… • What we think can be based on incorrect reasoning. • Things can ‘look’ a certain way to us – yet actually this may be complete fiction! • Answers are not always obvious – we have to actively search them out. • Critical thinking examines claims & conclusions & theories by comparing them to the evidence.

The problem with science is… • Research studies Ø start with different definitions Ø vary in quality Ø vary in aims Ø contradict each other Ø use different methods Ø vary in degrees of control Ø vary in scope • As such, claims are open to rival interpretations -- but these are not always obvious. • Sometimes the same evidence can support different conclusions!

What is critical thinking? • Critical thinking is not about being negative – to find fault and flaw • Critical thinking is about applying a level of doubt. • It is not a belief – it is a process of insight and understanding. • It does not force a conclusion on you, it just gives you a useful method to examine and evaluate it. …it is not always obvious what the truth is. Pic: Skeptical Inquirer

The Illusion of the right answer • Students get frustrated because all they want to know is; “what is the right answer? ” • However, it is not always clear what the correct answer is! In science there are few if any questions that have a “right” answer. • It is a case of finding arguments, based on quality, relative to competing arguments. • Facts do not speak for themselves – they require argumentation.

Why do we need critical thinking? Example: • On average Dutch people are the tallest population in the world. Reason – I know a few Dutch people and they are all over 6 -feet tall. or • On average Dutch people are the tallest population in the world. Reason – Scientific surveys have shown this to be the case by measuring height for Dutch people relative to all other groups and shown them to be statistically taller. Ø Which argument do you find most convincing…and why?

Critical thinking and argument Scientific accounts and theories are based on arguments. An argument is the putting forward of a reasoned case Critical thinking = examining and generating arguments A simple argument consists of: Reasons + conclusions = argument.

Critical thinking: An example A popular claim made by the media is that we only use 10% of our brains. Is it true? Characterise the argument correctly: The argument being made is that we only use 10% of our brain Or we do not use 90% of our brains. Now think about the logic of the argument and what it predicts…. . are these supported? Prediction – we could damage large sections (90%) of the brain without there being any functional impairment Prediction – we could remove 90% of the brain without there being any adverse consequences. So, what does the evidence say? Evolution – why develop something and only use 10% of it? Fuel – uses a lot of blood & oxygen – does not fit with the idea only 10% is being used – it should be more economical. Neuropsychology – localized damage anywhere in the brain can have severe implications for cognition Neuroscience (brain-imaging) -- no part of the brain is truly inactive during different tasks Is there any evidence in support of the claim – and if so, what is the quality of it? Anecdotal poor quality claims from uninformed sources.

Logic: an arguement must be both valid and sound: • Is this statement valid? Yes – this statement is valid! Validity only concerns the flow of the valid argument. • It is not sound as it is based on an initial premise that is NOT true. • We should never accept any argument that is unsound

Science Systematized knowledge derived from observation, study and experimentation carried on in order to determine the nature or principles of what is being studied

Observation • the first step in the process of science è Natural History (not history) – observe/sense the world around you. This is valuable science! • provides the ideas to generate hypotheses Scientific Method èHypothesis: provides tentative explanations, testable. èPrediction Carry out a test to see if predicted event occurs. SUPPORT or NOT SUPPORT proof

Experimentation ”manipulate” one or few variables and measure response variable (or dependent variable) control and replication Benefits: establishes probable causation Drawbacks: usually on small scale (or very expensive), may be overly artificial Experiments are just as often observational. ******************* Occam’s Razor = parsimony

CORRELATIONS http: //www. tylervigen. com/ Correlation -- can be done across space e. g. survey a large number of lakes -- can be done across time, e. g. sample one lake for many years benefits • can be predictive • can establish association, (e. g. low cancer associated with high fiber diet) • can be done in real ecosystems drawbacks • does not establish causation

An evolutionary question: Why Do Giraffes Have Long Necks? “food competition hypothesis”

“sexual competition hypothesis” alternative hypothesis https: //www. youtube. com/watch? v=60 SZ 7 Hk 0 wd. Q Experiments…?