Evidence

Evidence is material, acceptable to the audience, presented in support of claims.

There are some key features to attend to.

1. Evidence isn't just anything/everything you can find and present. If the material is not acceptable to the audience, it won't serve as support for claims, so doesn't stand as "evidence." Think of the courtroom analogy when a judge, for whatever reason, refuses to allow a piece of evidence to enter the case (even though the lawyers spent a lot of time finding/working up the evidence).

2. The acceptability of evidence depends on a number of factors, including

a. The reliability of the source. If the audience doesn't find the source "credible," the material provided by that source won't serve as evidence. For that to happen, the audience often has to know who/what the source is, how they know (why are they expert?), that they aren't overly biased on the issue (that they don't have a lot to gain from their position), and that the material has been taken from the source accurately and fully enough to not be "taken out of context" (among other tests).

b. The currency of the material. Although new material is not always better than old material (sometimes history matters and often background gives context to a question), not knowing about and presenting the most current information about the matter can serious undermine the credibility of the person making the claim and supporting it with old evidence.

c. The applicability of the evidence to the claim. We will look, later, at some of the ways evidence is applied to claims via reasoning/warrants. But for now, suffice to say that evidence is not just the material you present "after" making a claim. The audience will have to see the connection between the evidence and the claim. So in addition to the logical issues we'll take up later with reasoning/warrants, the evidence has to be appropriate to the kind of claim that you made. For example, if you've made a fact claim about the size of something, providing measurements as evidence fits better than providing a discussion of the quality of the materials used.

d. Presentation matters. As with everything in communication, if the material isn't presented clearly, the audience will have a difficult time applying the evidence to the claim the way(s) that you present evidence are crucial to their uptake and effects.

e. Documentation. Whenever evidence is used, it has to be presented following the normative "rules" of the genre in which it is presented. Courts have rules of evidence, medical diagnosis and treatment decisions are made based on satisfactoryly determined sets of symptoms. In scholarly writing, one has to provide clear indications for the sources of the material, otherwise, the audience might come to think that we are "just making it up" and "don't really know the facts of the matter" so might dismiss our claims. Documentation is tied to credibility.

There are many kinds of evidence. Including:

Expert Testimony: the quoted, spoken, words of a content expert on the matter of interest. Their "bona fides" (certified qualifications by degree and/or direct experience at high levels) matter.

Expert Quotation: the quoted, written words of a content expert on the matter of interest. Their "bona fides" (certified qualifications by degree and/or direct experience at high levels) matter.

One can also present testimony and/or quotation from sources that are not "expert." These could include reporters, participants, and witnesses. Obviously, as crediblity is lowered by lack of expertise, direct experience, or personal bias based on self-interest, the persuasive effects of the material are lowered.

Physical evidence: Material objects (when used in written papers, represented via pictures).

Scientific evidence: Reports of findings from scientific research, study, and testing. One has to be careful to present theories as theories rather than as fact. Remember that science "indicates," at (hopefully) high rates of certainty, rather than "proves."

Statistics and numerical analysis (including the charts/tables/graphs/spreadsheets that help audiences understand the numbers). The numbers represented could be actual counts or projections/interpolations (and which is the case, matters a lot).

Examples: stories of incidents. These range from eye witness news reports of events rendered by professional reporters to "tall tales" (almost fables) spun by "folks" who claim to have been there or who claim to "know." Obviously, the quality of the example as evidence varies based on the degree to which the events actually happened and the story through which the example is presented is accurate and believable. Hypothetical examples are usually very weak evidence, lending them more to story-telling than to argumentation. Personal examples are usually very weak, due to the obvious bias factor in that the person making the claim is also serving as the source for the evidence.

It's always good to remember that your evidence may lead to the audience being convinced of your claims because you've provided proof. It's NOT recommended that you conclude you've "proven" your claim. Providing proof (evidence) helps your audience decide about the claim; saying that you've "proven" it, often causes your audience to have to decide more about whether they want to go that far (it's been proven) than considering the validity of your claim.

When your reading summary is targeted at analyzing EVIDENCE, I want you to identify and evaluate the evidence that the author uses to substantiate claims made in the assigned section.

1) summarize the reading

2) List and describe three different types of evidence presented in the reading:

a) Example

b) Expert testimony or quotation (use and identify one of these two types)

c) Statistics or numerical analysis (use and identify one of these two types)

For each, briefly discuss how the evidence supports the claim it is related to and critique the quality of the evidence as presented.

An example:

Protocols tie together diverse networks and govern communication between all computers on the internet. Grad students were given the responsibility by ARPA to develop protocols in 1969. These students worked over the internet on technical protocols, but began to establish informal protocols. Because these graduate students were working on something so import for the network, Steve Crocker wrote the first RFC to make collaboration on the internet easier. This meant that anyone could help develop the technical protocol. This RFC set the tone for the future of Internet culture, and started the process of defining the protocols that govern all data exchanges on the planet. There are now thousands of RFCs and they maintain that open, collaborative approach towards internet engineering that Crocker intended.

In 1979, SRI, parked in Zott’s beer garden, created PRNET. They sent the first packet data transmission across two networks using the new “internet” protocol. The discovery of transmission being sent across networks arose from an earlier project at the University of Hawaii in 1970. Abramson wanted to connect all seven campus together using radio, verses ARPANET. Abramson’s project lead to the development of the first packet radio network, which ARPANET latter used to build PRNET. Then ARPA began developing a way to connect networks via satellite. They initially used NORSAR’s satellite to connect to the University College London to ARPANET. Then in 1975, with the help of the UK post office, ARPA initiated SATNET. ARPA had successful built three functioning networks by the end on the 70s: ARPANET, PRNET, and SATNET. Following the development of these three networks, PUPs was created to share information that was controlled by the computers/devices, rather than the connecting infrastructure (IMPs). Then TCP was developed to connect different devices on different networks in a “dumb” way, utilizing the host rather than an IMP. Then IP was created to handle internetwork connections between networks. Cerf tested internetworking using TCP and IP, and it worked great.

After a long time, telephone companies finally saw the potential of digital packet-switched networks. AT&T still wanted to maintain control over their network so they developed their own protocol, x.25. Many other protocols were developed as well. TCP/IP’s interest was in public data networks, rather than the specific approach that the telephone companies took. Because TCP/IP was more general it would maintain its high rank among the protocols of that time.

Examples of Evidence:

Expert Testimony – “’I had to work in a bathroom so as not to disturb the friends I was staying with, who were all asleep” (Crocker, pg 32).


In the book, the author is describing how the protocols that as super important to the internet as we know it today were developed during humble circumstances. In this case, Crocker said that he was working on it in the bathroom. Crocker’s quote is expert testimony because he is an expert. He was the one who was working on the protocols, and he said the quote that the author uses to support the claim that the protocols were being written during humble circumstances, therefore; this is an example of expert testimony.


Example – The author tells of the first test of TCP/IP conducted in 1977 to support the claim that ARPA had successful linked ARPANET, PRNET, and SATNET (pg 40).


This story is an Example because it informs the reader that TCP/IP is great. The story gives a specific example in which SRI drives their van around California using radio to connect to the ARPANET, which connected to a machine on the east coast, which was connect to SATNET without any errors.


Statistical/Numerical – “In 1969 Senate Majority Leader Mike Mansfield had signaled his intention to cut $400 million from defense research budget (pg. 35).


This is an example of numerical evidence because it clearly explains that 400 million dollars were cut from the defense’s research budget.