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Basic Debating: Determining Credibility

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Thu Jul 03, 2014 1:51 am
Kale says...

Credibility is important in debates. The more credible a side is, the more difficult it is to argue against that side. As a result, being able to determine the credibility of the other side(s) and the sources used is essential to effectively arguing your own side of an issue because if you can show that the other side's supporting evidence lacks credibility, then that side's argument is weakened.

There are four main criteria for determining credibility:

    Biases and Interests
    Distance from the Original Source


All good arguments are logical in progression, and all logical arguments are valid. As a result, if an argument doesn't progress logically, that argument is invalid.

The following is a valid argument:

P1: Cats are animals.
P2: Dogs are animals.
C: Cats are dogs.

However, as you can clearly see, just because an argument is valid, that argument is not necessarily true. This is where the second criterion comes in...


An argument is sound if it is both logically valid and factually true. While the above example is valid, it is clearly not true, and so that argument is unsound and therefore not credible.

This is where sources come into play, as soundness cannot be determined without pulling information from external sources. However, not all sources are equal, which leads into the third criterion...

Biases and Interests

All sources are biased. However, the extent to which these biases affect the source varies, and in general, less biased sources are more likely to contain truthful information than heavily biased sources. Additionally, the more self-interest is involved in a source, generally the more biased the source is.

It is worth noting, however, that bias is not always a bad thing, and bias alone does not discredit a source. While bias and self-interest in scientific papers can (and often does) discredit the results of the research done, bias and self-interest in subjective areas, such as personal experiences, can actually strengthen the credibility of a source.

One way to counter the biases/interests inherent in sources is to reference multiple sources with different biases/interests. The more sources that are in agreement on a point in spite of their biases/interests, the more likely that point is to be true. If all sources agreeing on a point share the same biases/interests, however, it's usually a safe bet to make that the biases/interests have undermined the credibility of the sources.

Distance from the Original Source

The last criterion for determining credibility is based on how far removed from the original source a referenced source is. There are three main categories of distance:

Primary sources are directly from those that observed or recorded a phenomenon and are considered to be the original source. Examples include a paper publishing the results of an experiment, personal anecdotes, and raw data collected from an instrument.

Secondary sources have had direct contact with primary sources, but no direct contact with the recorded phenomenon. Examples include peer reviews of an experiment's results, a person relaying what a friend said, and recorded interviews.

Tertiary sources have had direct contact with secondary or other tertiary sources, but no direct contact with primary sources or the recorded phenomenon. Most sources are tertiary sources, and examples include encyclopedias, dictionaries, and friend-of-a-friend anecdotes.

In general, primary sources are the most inherently credible, unless their biases/interests discredit them. Secondary and tertiary sources, as a result, tend to be considered less inherently credible as they are more indirect and rely upon the credibility of the primary source, with tertiary sources being the least inherently credible. It is worth noting that, as with biased sources, the more secondary and tertiary sources agree upon a point, the more credible that point becomes unless those sources all rely upon the same primary source.

Various Notes

The biases/interests and distance from the original are closely related, with their credibility hinging upon whether or not the biases/interests or distance adversely effects the point(s) the source presents. Distance from the original source can introduce new biases/interests and/or ameliorate the effects of original biases/interests.

Validity and soundness apply to sources as well. If the arguments used in a source are invalid/unsound, then that source is effectively discredited.

Pointing out that the other side(s)'s arguments are invalid, unsound, too biased/self-interested, and/or rely entirely on sources that can be discredited is a valid method of discrediting the other side(s).
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There are no chickens in Hyrule.
Princessence: A LMS Project

The strongest people are not those who show their true strength in front of us but those who win battles we know nothing about.
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