My first post. It is a bit hand wavy and way, way overdue (Sorry, Matthew). Again, thanks for the warm welcome earlier. Now that we've made nice, feel free to explain how I'm missing something terribly obvious.
I saw that the opening rounds of the Draper/Plantinga debate have been posted over at The Secular Web (HT to JD). I wanted to look at Plantinga's evolutionary argument against naturalism (EAAN), which can be stated as follows.
Let R be the proposition that our cognitive faculties are reliable, N the proposition that naturalism is true, and E the proposition that our cognitive faculties have resulted from processes of the sort described by contemporary evolutionary theory. Plantinga argues as follows:
(1) P(R/N&E) is low or inscrutable.
(2) Informed naturalists (i.e., naturalists who grasp the truth of (1)) cannot rationally believe that R is true.
(C) Informed naturalists cannot rationally hold any beliefs at all, including their belief in naturalism.
To hear Plantinga tell it, the effects of accepting (1) are epistemically catastrophic for the evolutionary naturalist. There is something about this argument that has troubled me, and I can see that it bothers Draper as well. Suppose you accept (1) because you think that P(R/N&E) is inscrutable. What of it? Does it truly follow that you have a defeater for N&E?
To say 'Yes' suggests that you accept something along these lines. If we say your evidence consists of EVI, you can be rational in continuing to hold the beliefs contained in EVI only if you can assign a high value to P(R/EVI). But that seems like a mistake. Surely as our beliefs 'built up' over time, we accepted beliefs backed by experiences and memories such that we could not assign a high value to P(R/EVI). The thought that you can rationally accept EVI only if you can assign a high value to P(R/EVI) not only appears to have the untoward sceptical implication that few of us could have acquired the beliefs we would need to justifiably hold to make an informed judgment about the respective merits of, say, theism and evolutionary naturalism, it seems awfully close to committing a kind of levels-confusion. If you think that the truth of R is a necessary condition on having justified beliefs produced by the faculties that are mentioned in R and combined that with the view that you'd have a defeater for any set of beliefs on which you could not rationally assign a high value to P(R/those beliefs), it seems for those beliefs to be justified, you'd have to be in a position to justifiably believe that the conditions for justification obtained for such beliefs. If, however, you think that this further requirement is not necessary for justification, why would it matter that you could not assign a high value to P(R/those beliefs)?
Regardless of whether you agree with Draper (and myself) that there is something fishy going on here with the inference from (1) to (2), Plantinga has made a move that I find rather surprising. I haven't followed the development of his EEAN as closely as some, but the new version of the argument he's offering replaces (1) with:
(1') P(R/N&E) is low.
Problem solved. If Plantinga can justify (1') maybe evolutionary naturalists are really in hot water.
Draper doubts (as do I), that it is unlikely that R is true given that our ancestors were not weeded out by evolutionary forces. Fitness does not guarantee reliability, but on its face, the possibility that creatures of the kind we take ourselves to be (slow, soft, delicious to predators, not equipped with poisonous spines, etc…) could have survived without relying on our wits seems rather remote. To defend (1'), Plantinga seems to concede something to Draper. He concedes that it is unlikely that our ancestors would not have been weeded out were it not the case that their behavior was fit _and_ they had something that indicated something about those aspects of the environment that needed to be indicated for our ancestors to navigate it successfully. What he suggests is that granting this much does not give us any right to say that the likelihood that such creatures would be equipped with reliable belief-forming mechanisms is high.
Perhaps I'm being naive, but it seems to me that the odds that our ancestors could have flourished and brought us here if they lacked reliable belief forming mechanisms seems low. Prima facie, it would seem to be nothing short of a miracle if Ug and his wife Ug could have lived past infancy, bred, and ensured that their children, Ug, Ug, and Ug, would live past infancy without reliable ways of determining the presence of predators, the location of food, ways of growing food, ways of staying warm, how to deliver babies, etc… To this, Plantinga's response seems to be somewhat concessive. He seems to grant to Draper that the long term survival of our species is reason to expect that their cognitive faculties were reliable. However, he thinks that this shows only that given that our ancestors' behavior was fit, it is likely that they had some reliable way of indicating how things were outside of them and how to satisfy their desires, but (and this seems key) it does not follow that it is likely that we had reliable ways of representing how things were in terms of our beliefs.
In a broad sense, a belief-less entity might have a reliable way of indicating the presence of food. Here, think of frogs and their behavior which requires a reliable fly detector. We don't have to assume that the frogs have beliefs about flies to explain their success. So, if we grant that some reliable action-guiding indicators suffice for explaining the success of behavior, it does not follow that having reliable belief-producing mechanisms is likely.
We can distinguish between the critters whose behavior is fit and fit (in part) because of indicators that guide behavior without producing belief (and, hence, without producing true belief reliably), but what I don't get is why such a possibility gives us reason to say that it is _unlikely_ that creatures that have such beliefs and such cognitive indicators guiding action have their beliefs reliably turn out to be true. I don't understand why the possibility of such creatures gives us reason to think that creatures that engage in the kind of complex behavior that we do and our ancestors did would have likely succeeded without reliable belief producing mechanisms. As he's granted that the onus is on him to show that the likelihood of R is _low_ granting what he's granted about successful behavior and the need for reliable indicators as to how the external environment is, I just don't see how he thinks he has carried out this task. I can see saying that the likelihood of R on the assumption that our ancestors' behavior was fit and more complicated than the simple creatures he discusses that get by on external world indicators might be inscrutable, but we're no longer to assume that this is a cause for concern. A belief's defeat is now taken to hang on a demonstration that it is unlikely to have been produced by reliable belief producing mechanisms.
A little help? Has Plantinga conceded too much to Draper?