Value Unit 01

Value of Evidence

Academic work and research is all about demonstrating to the reader that you have established a certain level of proof or evidence for your claims.  But what constitutes "proof" or a likelihood of "probability" is not such a simple task!  There are many levels and shades of proof; the following unit will introduce you 


Key Terms: Evidence

Evidence comes in different sizes!  All of your claims in an academic essay must be supported by evidence.  Providing such evidence fulfils your requirement to satisfy what is known as the “burden of proof” as you establish the probability or certainty of your claims. Study the key terms below to understand the elements of evidence in academic writing.

Burden of Proof

Whenever you make a controversial or disputable claim (such as "road safety is the most pressing issue facing our politicians today") you need to provide evidence or proof for your claims. This requirement that you provide suitable evidence is called “burden of proof”. Etymology of "Burden" >


To say that something is probable, is to claim that is likely. There are two kinds of probability: quantitative and qualitative (see next answers). In academic writing, probability is akin to likelihood: how likely something is to happen. Probability never rises to the level of proof or certainty. If something is 100% true or likely, it is beyond probability and is rather certain. Etymology of "Probability" >

Quantitative Probability

This is the likelihood of something happening based on mathematical or statistical factors. Typically, mathematical probability is calculated between 0 and 1, where 0 is impossible and 1 is certain. Quantitative probability is frequently described as a percentage: for example, “77% of salmon fail to spawn in pacific estuaries each August.” As a general rule, quantitative probabilities always require a citation in an academic essay. If, however, you have generated a statistic through your own research, then you need to explain your reasoning behind your results. Etymology of "Quantitative" >

Qualitative Probability

This is the likelihood of something happening based on experience, intuition, observation or philosophical or legal considerations. For example, the likelihood of rain increases with the presence of rain clouds and diminishes with the absence of rain clouds. Qualitative probability can also indicate what someone intends to do: “I plan to drive to Houston next week if I get my vacation” indicates a level of probability based on factors that are not necessarily statistically significant. Etymology of "Qualitative" >

Sufficient & Necessary Conditions

A sufficient condition means something which is enough to make something happen; a necessary condition is something which must happen for something else to happen. For example, you want to travel from Toronto to Montreal: it is necessary to get out of bed in order to travel, but it is not enough simply to get out of bed to go to Montreal from Toronto. At the same time, it is sufficient to get from Toronto to Montreal by boarding a plane or train in Toronto destined for Montreal. Necessary conditions are those that must happen in order to achieve a goal, but they are not enough on their own to make that happen. Sufficient conditions are those that are enough to make things happen, but they are not necessarily the only way to make something happen. Etymology of "Sufficient' > Etymology of "Necessary" >


Proof is evidence that shows something to be true. Proof should not be confused with probability or possibility. Proof establishes something as fact, beyond doubt, and is supported by irrefutable and repeatable evidence. A proof is 100% certain. In academic writing, proof is typically demonstrated through quantitative means (use of demonstrated statistics). Etymology of "Proof" >


This is the weakest form of evidence in academic writing. Many things are possible, even if they are very, very, unlikely. For example, it is possible that aliens will land on earth tomorrow at 10am and introduce us to a new extraterrestrial civilization...but this is very unlikely. You should not use “possible” things as evidence for cases you are making. In general, the concept of possibility should only be used in academic essays when establishing probabilities using quantitative methods. For example, you may wish to show that commercial flight throughout North America is statistically very safe and that while crashes are possible, they are not very likely. Etymology of "Possibility" >

Concept of "Truth"

The point of critical reading and critical writing is to determine the truth of something.  In fact, any writing or reading that is not aimed at the truth is contrary to our nature as human persons.


All too often, when we are writing or reading, we engage in what is known as “confirmation bias” whereby we only engage with material that supports preconceived notions about the topic of study.


“Confirmation bias” is so pervasive that most of us engage in it without even realizing it!  It requires a lot of effort and objectivity to avoid simply reading into texts that which we want to see, and relying on sources uncritically which support our preconceptions.

Avoiding Confirmation Bias

Often, we don’t think of critical reading and writing as having a “psychological component” but our mental state is a primary factor in the way we read and write.


Consider for example the very strong (and often adversarial) ways that people cling to political or social beliefs, and refuse to countenance any opposing views to those beliefs.


The best way to avoid confirmation bias is to distinguish between belief and evidence.  We often believe things without evidence, or assume things to be true simply because we have grown up hearing a certain narrative that has never been adequately explained or challenged.