Reading History #2 – Assumption and Inference

Assumptions are dangerous things to make, and like all dangerous things to make — bombs, for instance, or strawberry shortcake — if you make even the tiniest mistake you can find yourself in terrible trouble. Making assumptions simply means believing things are a certain way with little or no evidence that shows you are correct, and you can see at once how this can lead to terrible trouble. For instance, one morning you might wake up and make the assumption that your bed was in the same place that it always was, even though you would have no real evidence that this was so. But when you got out of your bed, you might discover that it had floated out to sea, and now you would be in terrible trouble. (Leminy Snicket, The Austere Academy)


The study of history requires much more than learning information, it demands a certain skill in assessing information and reaching informed conclusions, also known as inferences, about the past. Historical thinking, in other words, requires the sound application of analytical skills. Perfecting these skills demands the constant application of reason and is a process, that is it only develops over time and with practice.

Skilled thinking, like any other activity, requires practice that will often be difficult and challenging. Serious thinkers must learn how make their mind ‘move’ in the same way as a downhill skier or a tennis player learn how to make their body move: through constant practice, feedback, and adjustment. To make yourself a better skier, you need to know exactly how skies interact with the snow and spend hours of practice fine-tuning your edging skills. To make yourself a better thinker, you need to know how your brain mediates information and spend years (a lifetime even) striving to become more reasonable thinkers. How do we know what we know? How have we reached this conclusion (inference)? These are the first basic questions that all serious thinkers, and certainly anyone assessing historical phenomena, must ask. This investigation of our own thought is called epistemology, from the Greek epistēmē (knowledge), meaning the study of knowledge, and is fundamental to becoming a skilled thinker.

What we do when we make an inference (reach a conclusion) is to apply INDUCTIVE REASONING. The conclusion may be correct or incorrect, but let’s just stick with the process rather than assessing the validity of the conclusion just yet. We are bombarded with information constantly and our brain must absorb and sort through it all before reaching a conclusion and ‘deciding’ upon an action. Think of riding your bike down the sidewalk and suddenly confronting a barking dog that rushes at you from behind a hedge. You will, no doubt, take some sort of action quickly to avoid running directly into it. But what reasonable thinking were you doing during that brief moment? Your brain has, in an instant, taken in a great deal of information, made an inference about the situation, and come to a decision about evasive action. It has also done all of that while operating with a number of base assumptions about the event. What you might think is a mere physical reaction to the sudden appearance of the dog, is actually the result of a conclusion that you reached regarding your situation. Your brain worked in a fraction of a second, yet its conclusion was the result of a lifetime of sensory input and evaluation.

The ‘Ladder of Inference,’ first developed by a professor at Harvard Business School, is a good way to visualize what your brain does when you are confronted with information like the sudden approach of a dog. Here are the rungs of that mental ladder:

Step One: We receive information

Step Two: We select and filter specific bits of information

Step Three: We add meaning to the information based upon our beliefs and experiences, i.e. our assumptions about the world

Step Four: We make inferences from the meaning we have given to the information. These inferences often reinforce our already held beliefs.

Step Five: We take action based upon the inferences we’ve made

This is a natural progression of mental activity and, believe it or not, your mind filed through all of them in the brief moment that it took to react to the dog. If we skip some of the steps — jumping to conclusions — or fail to understand how our own assumptions inform our inferences, we are in serious danger of compromising the validity or cogency of our conclusions. This is a fancy way of saying that we make unreasonable inferences, in which case our historical thinking is flawed.

Let’s return to the example of the barking dog. Say you have had a bad experience with dogs in the past, perhaps the neighbor’s doberman bit you when you were a child. Your experience has informed your belief that dogs can be mean and dangerous. You may even assume that ALL dogs are mean and dangerous. Therefore, when a dog appears in front of your bike barking, you might jump to the conclusion, or infer, that this specific dog is also mean and dangerous. But are all dogs mean and dangerous? Your inference may or may not be valid. The important thing here is that you understand WHY you reached that conclusion. Perhaps more information is necessary in this particular instance. Is this particular dog snarling and bearing its teeth? In this example, you should see that both PRIOR EXPERIENCE (in the form of assumptions you carry with you) and IMMEDIATE DATA matter as you assess the situation before reaching a conclusion (making an inference).

In order to refine and improve your historical thinking, you need an awareness of the inferences you make and the assumptions upon which those inferences are based. ASSUMPTIONS are generally part of our unconscious thinking, they derive from personal experiences, our socialization, and the hard-wiring of our culture. Someone from another culture, or from another historical era, does not necessarily think with the same assumptions – it’s important to remember this when assessing information and sources. INFERENCES, on the other hand, are conscious opinions  and conclusions we make after receiving some specific information. For example, ask yourself what you might INFER from the following information?

  • There are black clouds in the sky. –> a storm is approaching
  • There is stopped traffic on the beltway –> an accident might have occurred up ahead / there may be construction ahead
  • Jay arrives at school with a black eye. –> he was injured in a rugby match / he got into a fight after school / he fell down the stairs

Now ask yourself what underlying assumptions led you to infer in such ways. Because all human thought is inferential, gaining command of your thinking demands understanding how you arrive at your inferences.

There are multiple ways you may have interpreted the information; not each one is valid, but each is possible. If you inferred that the traffic was backed up on the beltway due to an alien space-ship landing, then you are making an ungrounded inference, one not supported by any prior factual experience whatsoever. This, of course, is a serious flaw in reasonable thinking.

We make hundreds of inferences without knowing it, without really thinking about them, and without consciously engaging the assumptions that informed them. Most of them, we hope, are sound and justifiable: black clouds in the sky lead me to conclude that a storm is approaching. Some, however, are not: black clouds in the sky mean that evil spirits are approaching. Learning to think historically requires that our inferences be sound and justifiable, that is, they must be reasonable and supported by the evidence.

Some questions we need to ask ourselves, then, in order to develop more skilled thinking are:

  1. what assumptions do I have about the world and how do they influence how I assess information and reach conclusions?
  2. what is the real meaning (truth) of an event?
  3. would all reasonable and informed persons reach the same conclusions I do? Why or why not?
  4. are the ‘truths’ that I hold valid, that is, are they supported by evidence?
  5. am I willing to change my mind if confronted with better (i.e. more reasonable or more cogent) thinking?

Questioning our own thinking process should lead us to question whether or not our own assumptions are justified. Knowing that other people also have their own assumptions about the way the world works should lead us to become more skilled at analyzing historical information. and documents.

The Critical Thinking Foundation points out that we exhibit poor thinking when we:

  • jump to conclusions
  • fail to notice contradictions
  • accept inaccurate information
  • give vague answers
  • ignore information that does not support our position
  • distort data
  • come to unreasonable conclusions
  • misuse words
  • fail to see issues from viewpoints other than our own
  • are unaware of our own prejudices
  • communicate poorly
  • miss key ideas

EXERCISE:     read the following except from the Declaration of Independence written by Thomas Jefferson in 1776 and ask yourself the questions that follow.

IN CONGRESS, July 4, 1776.

The unanimous Declaration of the thirteen united States of America,

When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature’s God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation. We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.–That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, –That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness. 

  1. Can we infer that Jefferson believed in God?
  2. Can we infer that Jefferson was a Christian?
  3. Can we infer that Jefferson believed that human rights are granted by government?
  4. Can we infer that Jefferson thought that human rights originate in democracy?
  5. Can we infer that Jefferson thought that government receives its authority from the citizens it serves?

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