Presentation on theme: "That is a bear track A bear has passed this way. What is the nature of the transition from the first of these thoughts to the second? Is it DeductionInductionAbduction."— Presentation transcript:
That is a bear track A bear has passed this way. What is the nature of the transition from the first of these thoughts to the second? Is it DeductionInductionAbduction ? Are induction and abduction (i)the same form of inference differently expressed; (ii)different forms of inference but with a common form of justification; (iii)different forms of inference with different justifications.
Walton claims that induction and abduction are different forms of inference with different justifications, i.e., (iii). Abduction is a species of presumptive reasoning, and presumptive reasoning is (according to Walton) a form of reasoning distinct from inductive and deductive reasoning Fumerton claims that the validity of the argument There is a bear track A bear has passed this way is due to the validity of the inductive argument In all (or most) cases in which we have observed bear tracks there were bears present just prior to the existence of the tracks Here is another case of bear tracks A bear was present just prior to the existence of these tracks To establish (i) above, we have to establish that these two arguments are the same, that the arguer who offers the first as his argument means the second and considers these interchangeable, or perhaps one as a shorthand for the other. This is the case if the inductive argument is a reduction of the abductive argument, as Fumerton says at first. However, he correctly seems to suggest that the fact that both arguments are coextensive in their consequences does not mean that they are literally the same. He argues for the plausibility of (i) but commits himself only to (ii). To establish (ii) above, we have to establish only that the second argument is the justifier of the first. Here is an example of something that satisfies (ii) An inductive argument can be given for the reliability of something taken to have epistemic authority, whether it is an expert or a crystal ball. It does not follow that appeal to that authority necessarily amounts to giving that inductive argument as grounds for the conclusion. The arguer might give such an argument, but when she does, she is giving a different argument to that already given.
Abduction is a materially valid deduction I believe that both Walton and Fumerton are incorrect. When the conclusion “A bear passed this way” is uttered an argument is not being given or an inference being drawn, but there is a mere repetition of part of the content of “There is a bear track”. For there is no such thing as a bear track that is not caused by the passing of a bear, because of what it means to be a bear track. This does not mean that the utterer of “There is a bear track” will readily also utter “A bear passed this way recently” because these are different sentences. This is irrelevant to the claim of whether the hiker believes in a dispositional sense that a bear passed this way. To have the belief that there is a bear track is to believe that a bear passed that way, causing a bear track. Strictly speaking, this shows all that I need to show in this example. What the grounds are for believing the original premise “There is a bear track” is a separate question to how one gets from “There is a bear track” to “A bear passed this way”, which I have shown to be a priori. But I will consider this question anyway.
“There is a bear track” can be, I think, a basic belief, especially for someone who has become skilled at tracking, making it a kind of theory-laden observation. Of course, such a basic belief may be mistaken, and for this reason epistemologists who favour a strong foundationalist theory of knowledge will deny that they can be basic beliefs. They may say instead that although people say things like “There is a bear track”, they are saying more than they strictly mean and that is given by their mental representations. But strong foundationalism is an obsolescent theory. Abduction is a materially valid deduction Suppose that the hiker is forced to concede that he does not know that it is a bear track and abandons it as a premise, arguing instead along the lines of There is something that looks like a bear track A bear probably passed this way This could be made into an inductive argument by adding the unexpressed premise “Most things that look like bear tracks are bear tracks”. But this premise is, I claim, analytic because of what it means to be a bear track, thus the argument is materially valid even without the mediation of the general statement.
Concluding about new instances without using general statements Suppose now that the hiker is inexperienced and his basic belief is only “There is a track of a large animal.” Is it possible for him to get from there to “There is a bear track” or “There is something that looks like a bear track” without use of a general statement? There are two cases where this seems to occur. 1.When all or most of the hiker’s experiences of large animals and/or their tracks in his current epistemic context have been experiences of bears and/or their tracks. 2.When the hiker is told there are bears present but has not directly experienced them. He is nevertheless justified in believing what he is told once he has taken the information as seriously intended. This itself is an a priori abduction that turns out be similar to what Walton calls a parascheme. Walton’s parascheme for argument from expert opinion is given as: E is an expert E asserts A A is true This abbreviated version is less reliable than the full argumentation scheme because it does not consider critical questions or implicit premises. But, I would add, the parascheme can be abbreviated further as: A is an expert opinion A is probably true To perceive A as an expert opinion just is to perceive A as probably true; no inference is required and we do not need to go through the list of critical questions in order to labour the obvious point that the expert must be an expert. If the expert is not an expert then A is not an expert opinion, simply because of what it means to be an expert opinion.
Coherence, Explanatoriness, and Induction We are more inclined to take what we believe to be true as more likely to be true the more we take our beliefs to be coherent. By “coherent” is meant not only must the beliefs be logically compatible but should be probabilistically relevant to one another Having one belief should be a reason, however weak, for the other beliefs, and should never be a reason for the negation of a held belief. (1)That is a track made by a large animal, and (2) There are bears in the forest are only weakly relevant to one another (1)That is a track made by a bear, and (2) There are bears in the forest are more strongly relevant to one another Taking them to be mutually relevant inclines us to take them to have a common explanation, and this is to take there to be, or likely to be, a structure to the world. It is inductive methods that ultimately suggest to us what varies systematically and what is probabilistically relevant to what The success of inductive methods depends on the world’s being structured. So, it follows a priori from the existence of an explanation that induction is more likely to work. It is justified to believe that there is a track made by a bear if you know it is made by a large animal, a bear is a large animal, and bears are present.
1)The house dog is a highly-trained watchdog prepared to strongly bark to someone he senses has a dangerous character to their master´s house. 2)The masters of the house, are a couple who have a very light sleep. 3)The house was robbed while the dog was in the house and the couple were asleep. 4)The burglar was a friend of the couple, familiar to the dog.
1.I do not believe that this is not an inductive argument. 2.It relies on two counterfactuals: i.If the dog had barked, then the couple would have woken. But the couple did not awaken, therefore (probably) the dog did not bark. ii.If the robber had not been familiar to the dog, then it would have barked. But the dog (probably) did not bark, therefore (probably) the robber was familiar to the dog
3.These counterfactuals are true if and only if: i.On most occasions when there is a loud noise, the couple awaken. If they did not, then they would not be light sleepers by definition and premise (2) would be false. ii.On most occasions when there is a man of dangerous character present, the dog barks. If it did not, then it would not be a highly trained watchdog by definition and premise (1) would be false. 4.Note that 3(i) and 3(ii) are frequency ratios, i.e., probabilities. The reasoning is inductive.