If you see someone committing a logical fallacy online, link them to the relevant fallacy People will often commit logical fallacies as a way to trick others into. Strong arguments are void of logical fallacies, whilst arguments that are weak tend to use logical fallacies to appear stronger than they are. They're like tricks or . This book is aimed at newcomers to the field of logical reasoning, particularly those who, The literature on logic and logical fallacies is wide and exhaustive.
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The Ultimate Collection of Over Logical Fallacies, by Bo Bennett, PhD. Master List of Logical Fallacies. Preparation for College Composition. From Class : 1. Ad Hominem a. Definition: An attack on the person making the argument. COMMON LOGICAL. FALLACIES fallacy: an error in reasoning due to a misconception or False dilemma or the fallacy of insufficient options. ▻ The arguer.
Though the form of the argument may be relevant, fallacies of this type are the "types of mistakes in reasoning that arise from the mishandling of the content of the propositions constituting the argument".
Here the most important issue concerns inductive strength or methodology for example, statistical inference. In the absence of sufficient evidence, drawing conclusions based on induction is unwarranted and fallacious. With the backing of empirical evidence , however, the conclusions may become warranted and convincing at which point the arguments are no longer considered fallacious.
Hasty generalisation often follows a pattern such as: X is true for A. X is true for B. Therefore, X is true for C, D, etc. While never a valid logical deduction, if such an inference can be made on statistical grounds, it may nonetheless be convincing. This is because with enough empirical evidence, the generalization is no longer a hasty one.
Relevance fallacy[ edit ] The fallacies of relevance are a broad class of informal fallacies see the navbox below , generically represented by missing the point : Presenting an argument, which may be sound , but fails to address the issue in question. Argumentum ex silentio[ edit ] An argument from silence features an unwarranted conclusion advanced based on the absence of data.
Sometimes one event really does cause another one that comes later—for example, if I register for a class, and my name later appears on the roll, it's true that the first event caused the one that came later. But sometimes two events that seem related in time aren't really related as cause and event.
That is, temporal correlation doesn't necessarily entail causation. Slippery slope[ edit ] Definition: The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but in fact there is not enough evidence for that assumption.
It is also important to observe that both of these fallacies are arguments. That is, there is a structure to each of them comprised of premises and conclusions.
It is important to keep the difference between them clear. Consider the following: In the conclusion to a paper defending attacks on introduced species, Daniel Simberloff writes: This said, I must address what I believe is a red herring introduced by a philosopher Sagoff and two ecologists Slobodkin ; Rosenzweig Although some extreme adherents of an aesthetic stance favoring native species doubtless hold such a view, invasion biologists do not, and the many recent government and international activities on introduced species explicitly recognize the enormous benefits of some introduced species.
Simberloff , p. Thus, the disagreement is not being engaged as it should. But by identifying the error that is involved here we have a better sense of why that engagement is failing—not because of a diversion away from the issue, but because of a misrepresentation of what is at stake.
An example in a paper by Richardson and Ricciardi represents a similar case. Richardson and Ricciardi , p. So we do not actually see the argument that conveys the caricature with which Richardson and Ricciardi disagree.
Again, in the interests of the debate itself readers should be presented with the argument in order to assess things for themselves. One important feature of the debate, then, is over the control of definitions and the descriptions of the disagreements themselves. Such perceptions are often based on a few famous examples of invasive species, such as the brown tree snake in Guam or the zebra mussels in North America, which are known to cause certain problems in the ecosystems where they have been introduced.
Discussions of new species introductions frequently begin with a reminder of the negative effects caused by these relatively few notorious invaders, and this creates the impression that any, or many, non-native species could cause devastating damage to the environment and native species, even though this is usually unlikely, and not proven, in most cases. This approach is obviously prejudicial, since it can generate hostile attitudes and lead to potential control programs against species which may be quite harmless, or may even, if given the opportunity, bring some positive contributions to their new surroundings.
The two species may have nothing in common, except for having a presumed non-native status. But we can see that the principle involved is the same: there is an alleged association between parties in this case species.
We cannot dismiss the possibility that there are cases in which such a transfer would be reasonable, where an association does exist. But our point is that the association should not be simply assumed.
In fact, it extends the prejudicial nature of much of the debate by appearing to encourage what it actually precludes. As we saw in the previous section, prominent invasion biologists often defend their field by stating that they are not against all introduced species—just against the ones with a negative environmental impact Simberloff ; Simberloff et al.
Usually, species—native or introduced—have a variety of environmental impacts—some positive and some negative, depending on our points of view and which particular aspects and interactions we choose to focus on. There has been a general tendency in invasion biology to focus mainly on the negative impacts of species perceived as introduced. Aside from this practical concern there is a logical problem of equal import. Ruesink et al. They judge the most effective way to reduce harm is to assume that all nonindigenous species are threats.
On the face of things, this seems like a clear requirement with a condition that must be met.
But in practice, it is no condition at all because on the terms that the authors themselves have established it is a condition that can never be met. At some future time it is logically possible that a problem can emerge. And thus further, nonindigenous species cannot be proven innocent and so must always be deemed guilty. There are various ways of presenting the fallacy at the heart of this policy.
However we understand this, we should appreciate the logical problem of presenting a condition that can never really be met. In drawing attention to this, we equally draw attention to the need for serious work to be done in the middle ground between the two extremes of assuming complete innocence and complete guilt.
For example, as Davis et al. Also, Venter et al. In fact, introduced species were the least important threat among the six categories examined in that study. So, destructiveness and damage to the environment or the economy are not attributes associated solely with, or identifying features of, non-native species Davis et al.
Many introduced species are not guilty of causing any such environmental or economic problems. This editorial was titled Misleading criticisms of invasion science: a field guide. The rebuttals are given in considerably more detail than the actual criticisms, and there is no way to decide, based on the limited information provided, whether the sources cited in support of the rebuttals provide comprehensive and convincing responses to each of the criticisms of the field.
The impression given is that each of the criticisms listed in the table is without merit, and has been fully addressed and debunked in the relevant literature. However, that is not the case. At least some of the already meagre sources cited for the rebuttals are very brief opinion pieces which do not offer any new data—for example, the Wilson et al.
Furthermore, plenty of additional studies and examples could have been selected, and a more detailed and nuanced description of the criticisms of invasion biology could have been included, of course. Another table could have been put together just as easily, showing studies and data which contradicted the rebuttals presented by Richardson and Ricciardi In taking issue with the criticism that some control programs may be directed at non-native species that do not really cause any, or much, harm, Richardson and Ricciardi wrote: In reality, managers are constrained by limited resources and seek to prioritize species that are likely to become problematic.
However, this effort is hampered by several facts that are generally ignored by the naysayers: 1 the impacts of most invasions have not been studied, and so important effects may remain undetected, 2 invaders that are apparently innocuous in one region can be disruptive in other regions, 3 subtle impacts that may be unrecognizable without careful technical study can produce enormous ecosystem changes over time, and 4 many non-native species that currently appear innocuous may become damaging many years later — when it is no longer feasible to eradicate them.
What if we rush to judgement, and end up eradicating a species which would not have caused any harm, and may even have had a net positive impact, if we left it alone? However, that clearly does not mean we have to consider non-native species automatically as problematic when they appear in a new area, particularly if these species are not known to have had a negative impact anywhere. It is also possible that even introduced species which have acquired a bad reputation elsewhere may cause no problems in the regions we are interested in.
This is a two-way street. Subtle impacts may, theoretically, produce larger impacts over long periods of time, but just how long would these projected periods have to be before we decide we must act now?
If the impact of an introduced plant or animal will not be significant for hundreds or even thousands of years, it is obviously not of immediate concern. Who knows what current ecosystems will look like centuries or millennia from now?
Many other factors will affect these ecosystems over such long periods of time. Furthermore, sometimes the impacts of invasive species become less important over time. So, again, this works both ways. In some cases, the impact of an invasive species may be most significant immediately after the introduction.
After a few years, this impact may decline naturally, without our interference. This highlights the need for thorough and objective longer-term studies about the impact of non-native species, and suggests that we should be careful not to jump to possibly premature conclusions based only on very preliminary observations or short-term studies of such species Guiasu Changes in environmental conditions may cause a native species to become much more abundant and widespread than before as well.
Let us make up our mind, and let us all indicate clearly where we each stand on this. We cannot have it both ways.
Simberloff et al. The assumption that a currently harmless species should be controlled anyway could also lead to potentially bad management decisions, resulting, for example, in the squandering of limited resources to fight against a species which should not be of concern and the damage to the environment that may be caused by such misguided control programs.
For example, in New Zealand, poisons used to eliminate introduced mice also killed the North Island saddleback, a rare native forest bird Davidson and Armstrong In an article which attempted to find the middle-ground in some of the current debates about invasion biology, Shackelford et al.
Both sides have merit. This point sits at the center of much recent controversy. Without resource and methodological constraints, many, if not most, conservationists would still probably prefer to rid systems entirely of non-natives regardless of impact.
Shackelford et al. If a species—for example, purple loosestrife—has been declared to be a problem, in general, it is very likely that control or eradication campaigns will be attempted against that species at many locations where its impact may not be negative overall. It is doubtful that conservationists or managers in charge of individual conservation areas are always conducting their own thorough independent research to determine whether the introduced species present within their jurisdictions are having mostly negative, or positive, impacts.
And getting rid of non-native species entirely is clearly not a realistic goal, even assuming we could somehow identify all the non-native species in a given ecosystem, which would also be extremely unlikely. Moreover, researchers should not be accused of being ignorant of the relevant literature, willfully or otherwise, if they entertain such thoughts or make such suggestions and back them up with proper references and data.
In many cases, such species may have some negative short-term effects as well as some positive ones, and the long-term impacts may be unknown. Not all of these peer-reviewed articles point in the same direction or lead to the same conclusions.
Perhaps it could be said that Richardson and Ricciardi are ignoring some of the peer-reviewed literature in their field when they are making such general statements. And some of the invasion biology papers, published in peer-reviewed journals, are mere opinion pieces.
Such papers clearly add to the volume of the literature in this field, but they do not contribute any new evidence or data.
This shows there is no unanimity, or even a strong consensus, in the field with respect to the presence and role of non-native species. Young and Larson also found that there was almost equal support in the field for two different definitions of invasive species—one which stated that such species have negative environmental or socio-economic impacts and another one which did not.
As discussed, species can often have a variety of impacts—some positive and some negative—and choosing which particular impacts to focus on may depend on our particular points of view or interests. Invasion biologists themselves appear to be quite divided on some important issues and definitions in their own field. However, the critics of invasion biology whose work we are familiar with are not saying that introduced species cannot have negative impacts or that these impacts are always exaggerated.
Specific criticisms usually refer to particular species and examples. Nor can it be said that the negative impacts of non-native species are never exaggerated, or that the positive effects of these species are never ignored or understated in the invasion biology literature.
Quite a few studies, including several cited in this article, would suggest otherwise. The impact of the rusty crayfish in Ontario is another relevant example. Do we know enough about it to start the anti-rusty crayfish campaigns?
This species has been accused of having a negative impact on other crayfish species of the same genus. However, in a major study, Edwards et al. Rarely is positive information about invasive species included in the brochures, information sessions, guided nature tours, or lectures associated with, or influenced by, this field. Nor do many invasion biologists or wildlife managers set out to find out just how much of a good contribution exotic species can bring to various ecosystems.
What is the percentage of invasion biology studies which specifically focus on the positive attributes of non-native species? Non-native plants and animals generally do not have the same impacts as pathogens and dealing with illnesses which affect humans is the responsibility of medical professionals not invasion biologists.
In addition, funding for health care is usually separate from funding for programs against invasive species Guiasu Richardson and Ricciardi tend to describe the chosen criticisms of invasion biology in very general terms.
That is an overgeneralization, and, therefore, an exaggeration, or even a caricature, of the position taken by certain critics of the field. Just because some of us take a longer term and more generous view of non-native species and processes such as natural hybridization between native and exotic species, that does not mean we are oblivious to potential problems associated with the introduction of species.
And it may be worth keeping in mind that non-native species deserve to be known and studied for more than the potential problems they may sometimes cause, and, as previously mentioned, native species are perfectly capable of generating environmental and economic troubles as well. However, none of these three studies actually state that species introductions should not be of any concern, in general.
In fact, Brown and Sax and Vermeij recognize that some non-native species can have negative effects, at least in the short term. These authors also clearly indicate that the introduction of such species should not be encouraged.
Overall, Brown and Sax , Vermeij , and Thomas encourage a more objective and open-minded approach to the study of non-native species and their impacts, based on evidence collected over the longer term, and not just the short term.
Some authors consider introduced, or exotic, or non-native species to be those that have arrived in a particular area since the beginning of recorded human history, and native or indigenous species those that have either evolved in the region or moved there during prehistoric times Myers and Bazely Webb attributed native status to those species which had been present in the U. The problem with these and other similar definitions is obvious. It is often difficult or impossible to determine exactly how or when a particular species reached a certain area.
As one of many such examples, we can look at a recent debate about the status of some northern pike Esox lucius populations in Ireland. Until recently, this freshwater fish species was thought to have been introduced by people to Ireland during medieval times.