Scepticism and the Role of Evidence

Scepticism and Evidence

As indicated in previous blogs I am here presenting an overview on the nature of evidence. It is important to understand what constitutes evidence for a sceptic as this is what we turn to for validation of claims and assertions. The topic is quite complicated to cover as there is so much material around, I can only cover what is relevant to an everyday sceptic which I am assuming most of us are. Evidence is necessary if the claim or assertion is either complex, questionable, or maybe counterintuitive – however the claimant is obliged to supply the evidence. If they can’t supply evidence, then we can validly reject the claim. In many cases the evidence is weak, taken from a questionable source, – so sometimes the evidence itself needs checking.  We don’t really expect the everyday sceptic to make such complicated checks, but often other experts make evaluations that are available so it’s a matter of checking all sources.

As we have said the question of the nature of evidence or what constitutes evidence is central to the practice of scepticism. However, there appears to me to be a considerable lack of knowledge and even misinformation on what constitutes evidence. Often you find, especially in religious blogs, that quotation from some authority is regarded as sufficient. Religious blogs tend to use the bible or some other religious text as evidence to support their assertions. As I have said in other blogs it is not acceptable to support a claim by reference to statements made by the author of the claim. This is common in religious texts as they hold to the assumption that the bible is the literal word of God and you can’t quote a greater authority. This is circular and unacceptable for many reasons including the lack of evidence indicating that the bible is the literal word of god. Also, and obviously, the bible and biblical writers are biased in favour of their own assertions. If you’re going to use authorities, then you try to use disinterested authorities who have no bias either way. My point is that a sceptic not only has to demand evidence to support a proposition, but they also must check that evidence.

It is important for us to understand that we don’t have to check for evidence for all that we do in everyday life as we would end up doing nothing but checking evidence. But it is important to check assertions or claims that are controversial or otherwise important for us. Below I have listed different types of evidence as the type of evidence used depends on the nature of the claim.

What are the essential features of valid evidence?

I want to outline several the important features of evidence that are required by a sceptical stance. The discussion is not by any means exhaustive of the topic as there are several issues that we will not cover. Rather my aim is to present the nature and forms of evidence in as simple a form as I can.

  1. Avoid Bias

A crucial feature of all evidence is that it is objective, meaning not subjective such as unsupported claims by authorities or personal views. To be objective means the evidence lacks bias or the favouring of a certain result over another. The important aspect of this is that bias is often unconscious and the researcher may not be aware of their own bias. To counteract this, science in general aims to avoid bias by the adoption of methods that eliminate its possibility, in experimental science double-blind trails of medication are an example of this as the researcher has no idea of who is getting what. In fact, even outside of experimental science researchers of all stripes aim to eliminate bias.

2 Repeatability

This is a demand for example, that a repeat of the experiment will come up with the same result. This is essential in experimental science – if a different result is derived from a repeat of the experiment then the finding is seen as questionable.

Types of evidence

Evidence requirements vary according to the science or nature of the claims or assertions made.

  1. Experimental evidence

An experiment is a procedure (or a method) conducted under controlled conditions that enables one to determine the truth or otherwise of a hypothesis or assertion. Findings of an experiment are presented as a statistical analysis of the data acquired. Thus in medical science, for example, an experiment on the effectiveness of blood pressure medication may involve providing the medication to a selected group of individuals and a placebo (e.g a pill that does not contain the medication but looks like the ones that do) to a second (control) group in controlled conditions. The outcome sought is whether the group taking the medication experienced a drop in blood pressure whilst no such change was recorded for those receiving the placebo (the control group). These experiments can also be so constituted to show difference in gender, age etc. The value of the experimental approach is that it avoids bias by the experimenter by using controlled conditions.

b non-experimental evidence

This may also be what can be referred to as qualitative research, (though many scientists don’t like that term nowadays as many research projects include elements that can be referred to as both quantitative and qualitative). The subject matter of this research is not only the natural world but the world of customs, practices, values, viewpoints, and ways of thinking. This is research that seeks subjective information on individual’s opinions, choices, voting orientation and so on. It uses questionnaires, telephone polls, interviews to ascertain personal views. The information is collected and analysed mostly statistically to ascertain such information as trends in fashion, in thinking, people’s voting intentions, purchasing practices and opinions on certain issues. Statistical procedures are often used to collect data from interviews, polls, questionnaires Such research also has to beware of bias because in this area bias is sometimes harder to detect than in natural science research. The repeatability criteria can be checked by comparisons with other similar research for consistency etc.

C Anecdotal Evidence

Things to Know About Anecdotal evidence - YouTube

An anecdote is a story told by an individual about themselves; of an event that they experienced. It is sometimes referred to as a testimony in which the individual talks about such personal experiences. Normally, It is a personal experience story that another person cannot corroborate. For example, advertisements for certain products often include testimonials from people who claim they have successfully used the product. The goal of such testimonials is to encourage others to buy the product.

Anecdotal evidence is mostly unreliable in scientific studies as there is no way of objectively checking the story. One has to exercise a sceptical approach to advertisements and other media that contain testimonials as they are biased.

However, anecdotal evidence can be used as data in certain studies that ask for personal views or opinions. In these studies researchers may ask questions about personal views from a group of randomly selected individuals. Statistical techniques can be used to collate the data collected and then it can be analysed for trends and differences between individual groups such as by age, gender and so on.

In courts witnesses give evidence that is mostly anecdotal. It is the responsibility of defense lawyers to question witnesses about the evidence given to bring out any biases, forgotten facts, even lies. All this is done under oath so lies and deliberate fabrications can be regarded as perjury, a crime  that can result in jail terms.

d. Legal evidence

Documents and expert witness testimony can provide legal evidence. I will not deal in detail with all aspects of legal evidence as information is available on the web. I want instead to address the way we should deal with legal evidence as sceptics. Often legal decisions are met with considerable controversy mostly because there is considerable ignorance by the public of court processes and the use of evidence in convicting.

In courts there are rules of what counts as evidence (are admissible) in legal proceedings, as well as the quality and quantity of evidence that are necessary to fulfill the legal burden of proof. The types of legal evidence differ from scientific evidence somewhat. Testimony is evidence gathered from individuals that have observed the crime or have some personal knowledge of the person charged. The testimony is normally also in written form and signed in front of witnesses and given under oath. The witness can be charged with perjury if found to be lying. Types of legal evidence as well as testimony include documentary evidence, and scientific evidence. Expert witnesses can testify to the legitimacy of, for example, DNA samples. The courts can also use physical evidence (e.g. objects such as knives, guns).

The point I wanted to make here for an ordinary sceptical approach, the judge or jury making the judgment of guilt or otherwise must be convinced that the evidence indicates that the crime was committed beyond reasonable doubt.  Such a requirement is to protect an innocent person from being charged with a crime they did not commit. Reasonable doubt is a recognition that there was some doubt in the evidence given that they might not have committed the crime for which they were charged. Sometimes for the ordinary person in the street this may appear unfair as the general view is that the person charged was guilty. It is the case that the general view reflected in the media and especially social media is that the courts were wrong and biased or influenced by some authority.

To illustrate this, I will look at a recent case in Australia. This was trial of Cardinal Pell arguably the most senior catholic in the world accused of a sex crime. In fact, of two sex crimes on two young boys a month apart. The crimes were said to be committed in the same robing room (the sacristy) of the church where the cardinal was officiating. Evidence was taken from the victim of one of the ‘crimes’ the other victim unfortunately had committed suicide. The prosecution claimed that after the service the cardinal slipped away from the procession and entered the sacristy saw two boys there and managed to sexually assault them. The evidence from the surviving victim was said to be compelling however other witnesses such as the churches’ priest testified that the cardinal could not have committed the crimes as he was never alone and was in his company all the time when the crimes were supposed to have been committed. Despite this claim by the priest, the jury found the cardinal guilty and he was jailed. The case was subsequently appealed to the state Court of Appeal of three judges with two of them upholding the jury verdict the third arguing that there was reasonable doubt that the crime was not committed.

Subsequently, the case was appealed to the High Court of Australia the highest court in the land. They found unanimously (all 7 judges agreed) to many people’s surprise that there was indeed a reasonable doubt that the cardinal may not have committed the crimes due to the evidence that he was in the company of people all the time. The high court found that the victims account was credible but that the appeal court (and the County Court) had virtually disregarded evidence from those accompanying the cardinal at the time of the ’crimes’. Without going into detail, as the case is well covered by media, the high court found basically that too much credence was given the victims testimony while they did not take fully into account other evidence that the cardinal could not have committed the crimes. The case was quashed, and the cardinal was out of jail.

It was not found by the court that the cardinal did not commit the crimes, but the evidence was not adequate to convict him – beyond reasonable doubt.  The high Court decision was very controversial dividing the community. There were those who considered Justice was done and the cardinal was innocent. Others suggested conspiracies by the high court. It was claimed the judges were biased in favour of the cardinal as they were all Roman Catholics. Most of the social internet media considered him guilty.

What does a sceptic do in this case? A sceptic must be logical and make a judgement on what is available that is reliable. Let’s look at this.  

On reading the Judges decisions they were remarkably in agreement – all seven of them tended to note the same inadequacies of judgement. Secondly, I do not think the judges are all Catholics though I was unable to check this fully. However, my view is that if there was bias it could be bias in both directions for and against the cardinal.

This decision of the high court does not mean that the cardinal was innocent of the crimes but that in view of the evidence presented there was a reasonable doubt that he was not. We must be satisfied with that. This tells us something about evidence. That is it is not 100% conclusive. In most cases some doubt remains as evidence basically rules out conclusions rather than prove them.

To conclude this presentation, I will mention briefly a relatively new approach to evidence in the areas of professional practice.

Evidence based practice (EBP)

The beginnings of this approach can be traced back to the 1990’s in medical practice where is was known as Medical Based Practice. It is a process of transferring new medical research onto clinical practice. It was based on the view that medical practitioners and other health professional did not always translate new research finding about medication and practice approaches on the newest scientific evidence.

EBP came about after research indicated that many health practitioners were caught up in older practices and did not seek to integrate new research into best practice.  The idea is that new research can provide information or data that has relevance for professional practice and shows the best outcomes for users, patients and clients. Information presented by research cannot automatically translate into practice or clinical decision making but provide the latest information be used by professionals to enhance their practice and outcomes for patients. Evidence does not make or provide decisions or suggest outcomes for specific patients it simply provides the latest data on which such decisions can be based. A number methodologies have been developed to guide the translation of data into specific contexts. [1]

Two new forms of refereed articles have been developed for those who may not have the resources or time to look at all the research. The first is referred to as ‘systematic reviews’. Briefly these are articles that review the research literature on certain specific issues relevant to practice. They begin by setting up a research question (e.g. what is the outcome for using medication x and/or y for reducing symptoms of blood pressure?). The process involves using filters to eliminate research that is not fully relevant to the questions. Thus, they may sift out outdated research, only look at certain age groups and so on. Also, they look at the research methodology used and have a hierarchy of methodologies with random control trials at the top of the list. This latter, however, may not apply to qualitative type research that cannot use Random Controlled Trials, RCT’s.  It may result in the analyses of 30 articles from an original 200. They become a rich resource as professionals can see precisely what criteria was used for the analysis. Normally, the analysis is carried out by experienced researchers. Also, it is not difficult for non-professionals such as us ordinary sceptics to access and use these reviews. I will not go into this in detail but some RCT’s fall into a category of Meta-Analysis where the combined effects of studies are analysed. [2]

We will probably have to further address the nature of evidence in future presentations but hopefully we can now get started when we are confronted by some unsupported claim.

[1][1] See

[2] See

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