Plantinga's Evolutionary Argument Against Naturalism

[dakoski]

Hadn’t seen Plantinga’s Evolutionary Argument Against Naturalism as a thread (at least for a while) so thought it would be good to discuss.

Here’s the argument:

Premise 1: The probability of reliable cognition and reasoning is low or uncertain if evolution and naturalism are true.

Natural selection acts on hereditary traits that promote survival. Therefore, our cognitive and reasoning systems have not necessarily evolved to generate true inferences, but rather inferences that enhance our survival.

But isn’t the ability to generate true inferences by definition associated with greater probability of survival? Not necessarily, there are several reasons why this may not be the case. For example:

a) Error management theory argues that natural selection may favour avoidance of large risk at the expense of optimal logical inferences. An example atheists might like is that this theory can be used to support the high prevalence of false beliefs regarding theism, on the assumption that naturalism is true.

b) Neuroscience research suggests that higher serotonin is associated with over-optimistic bias. However, given the potential association between serotonin and depression, lower levels of serotonin may be associated with more accurate inferences but less adaptive.

c)For reductive materialists – human behaviour is determined by external factors as we do not have free will. In this context, its irrelevant to survival whether we are able to generate true inferences therefore there is no reason to think natural selection would select for reliable cognition and reasoning.

Premise 2: Anyone who believes that:
- naturalism and evolution are true
- naturalism and evolution are associated with a low or inscrutable probability of reliable cognition and reasoning
Have a defeater for their belief that their cognition and reasoning are reliable.

The obvious objection to this premise is that we know from experience that our cognition and reasoning are reliable. However this objection has a few limitations:

a) The argument is addressing the reliability of our cognition and reasoning – therefore we can’t use the conclusions of our cognition and reasoning to demonstrate the reliability of our cognition and reasoning (i.e. we’re engaging in circular reasoning)

b) The argument isn’t addressing the reliability of our cognition and reasoning given our experience, it’s addressing their reliability given the assumption that naturalism and evolution are true. The objection conflates these - they would first have to demonstrate the truth of naturalism for this objection to be valid.

Premise 3: Anyone who has a defeater for the belief that their cognition and reasoning are reliable – have a defeater for all their beliefs including naturalism. This follows from premise 2.

Premise 4: Anyone who believes both naturalism and evolution acquires a defeater for these beliefs. Therefore believing both naturalism and evolution is self-defeating and can’t be rationally accepted.

Question for debate:
Which premises do you agree or disagree with? Of course providing a rationale for accepting or rejecting the premises.

Some caveats:
1) Plantinga isn’t arguing that our cognition and reasoning are unreliable – that’s the point of the argument to show that naturalism is inconsistent with our experience of relatively reliable cognition and reasoning

2) Plantinga’s argument isn’t trying to refute evolution

[Divine Insight]

[Replying to post 25 by Divine Insight]

You went off on a bit of a tangent but the main point I think you were making was that if theism was true everyone would have the same level of cognitive ability.

I'll just repeat my previous response, where do you derive this hypothesis from? Its seems to just be a straw man.

But isn't that the gist of the whole argument?

The argument basically sounds to me like he's saying that Naturalism can't explain how humans could have evolved to have reliable cognition since he argues that reliable cognition isn't necessary for survival (a premise that wrongfully assumes that nothing can possibly evolve unless it is absolutely necessary for survival.) I've already explained the amoebas seem to survive quite well. So based on the above premise there would never be any need to evolved above the level of an amoeba. So clearly that premise is already wrong.

He also seems to be totally ignoring (or refusing to address) the consequences that we should expect if a divine creator had bestowed humans with reliable cognition by purposeful design. If that were the case then why shouldn't we expect all humans to have the same reliable cognition? Why would a divine creator have favored some humans over others?

It just seems to me that his reason for dismissing Naturalism is extremely weak, and there is no support for the alternative conclusion that he seems to be drawing.

As far as I can see he's basically doing nothing more than arguing the following:

"I don't understand how evolution works, so I'm going to jump to the conclusion that there must be purposeful design."

But his arguments don't support that conclusion.

[Bust Nak]

Couple of problems with this:
1) The assumption about the reliability of our senses and reasoning is grounded in a particular social, historical and epistemological context. The origins of modern science...

Come now, your suggestion here implies that before modern science, people seriously doubted the prowess of their sense and reasoning. No, people took their senses and thought for granted long before written history, let alone modern science.

Naturalism aims to keep these assumptions about our senses and reasoning but to deny the objective and coherent foundation from which these assumptions emerged.

And naturalism is the better for it - which is more parsimony? Assuming our senses and reasoning is somewhat accurate, or assuming there is a supernatural entity that granted us somewhat accurate senses and reasoning?

As you don’t seem to be denying Plantinga’s premises, it seems arbitrary to grant the reliability of our senses and reasoning. Why, given naturalism, would we think that’s the case? How can we know if our senses and reasoning are reliable given naturalism?

You seems to be going backwards, the presumption the accuracy of our senses and reasoning comes first, not naturalism.

Do you consider people who disagree about the objective validity of the scientific method and objectivity of truth to be wrong or just unconventional?

Wrong as in incorrect.

If they are wrong, how would you show they are wrong and you are right?

I refute it thus. *kicks a rock over* How could any reasoning work on someone who flatly rejects reason? How would you know that God didn't give you faulty senses and thinking? The point here is that the presumptions of reliability is unavoidable and naturalism makes fewer presumptions.

2) Your judgement about the apparent reliability of our senses and reasoning is based on our experience. So it’s not really answering the question of the reliability of our senses and reasoning, given naturalism. As we do not know that naturalism is true, unless of course you can demonstrate this objectively.

That's why the accuracy of our senses and reasoning is taken for granted.

So given our experience that our senses and reasoning appear to be able to generate objective true inferences about the world through the scientific method, doesn’t that also tell us something about the nature of reality?

Yes.

Is it not more likely that a worldview that can provide an objective and coherent grounding for our assumptions about truth and the scientific method better reflects reality than a worldview that cannot?

No, it is more likely that naturalism is true as it makes fewer assumptions than any other alternative, while still being useful, i.e. excluding solipsism.

[dakoski]

[Replying to Bust Nak]

Come now, your suggestion here implies that before modern science, people seriously doubted the prowess of their sense and reasoning. No, people took their senses and thought for granted long before written history, let alone modern science.

Several problems with your response.

1) Its common for atheists to assert that it was arbitrary that modern science emerged in medieval Europe. However, such assertions are contrary to the detailed research of historians of science who have shown the Christian context was one of the key factors that drove the origins of modern science. See for example the work of Edward Grant Foundation of Modern Science in the Middle Ages. Edward Harrison, the Fall of Man and the Foundations of Science.

2) There is some evidence that suggests reasoning may differ cross-culturally for example in studies comparing East Asian and Western participants. For example, it has been argued that Confucian values may explain some of the cross-cultural differences in these studies such as being more accepting of logical contradictions than Westerners, as well as tending to value intuition higher than analytical logic.

These data raise questions about the validity of arbitrary assertions about the objective validity of reasoning given naturalism. Given the potential role of social and contextual factors that impact on how we make inferences about our world it highlights the arbitrary nature of just assuming the objectivity of our cultural and social norms without first assessing whether this is warranted by the evidence.

And naturalism is the better for it - which is more parsimony? Assuming our senses and reasoning is somewhat accurate, or assuming there is a supernatural entity that granted us somewhat accurate senses and reasoning?

The problem with your argument is that when comparing different approaches we give much greater weight to logical coherence:

1) As you’ve not been able to dispute Plantinga’s argument above that if naturalism is true then it’s inscrutable whether our reasoning is reliable since natural selection selects for survival not reliability of reasoning.

2) There’s evidence that unreliable reasoning can be evolutionary adaptive. Then it’s logically incoherent to go against the evidence and assume our reasoning, if naturalism is true, would be reliable.

You have to first show that you’ve made a logically coherent argument that is consistent with available evidence. If you can’t do that then then parsimony is irrelevant.

You seems to be going backwards, the presumption the accuracy of our senses and reasoning comes first, not naturalism.

To make the judgement about whether our reasoning is reliable we have to know
1) something about the origins of our reasoning,

2)whether our assumptions about our reasoning are coherent with our other assumptions about reality. Such assumptions cannot be arbitrarily asserted within a vacuum.

Do you consider people who disagree about the objective validity of the scientific method and objectivity of truth to be wrong or just unconventional?

Wrong as in incorrect.

Why? You’ve acknowledged that the reliability of our senses and reasoning given naturalism is simply an arbitrary assumption. Why would such an arbitrary assumption be objectively true while other equally arbitrary assumptions wrong/incorrect?

I refute it thus. *kicks a rock over* How could any reasoning work on someone who flatly rejects reason? How would you know that God didn't give you faulty senses and thinking? The point here is that the presumptions of reliability is unavoidable and naturalism makes fewer presumptions.

Again, you’ve misunderstood the question. It’s not whether our reasoning is reliable, given our experience. It’s whether our reasoning is reliable given naturalism. Your response doesn’t answer the latter.

Why is presuming the reliability of our reasoning unavoidable? Clearly, some naturalists don't find it unavoidable. Including as I quoted above Charles Darwin. Are you OK with making arbitrary assumptions that are contrary to current available evidence?

The Christian worldview is coherent with my assumption that our reasoning is reliable but fallible. I’m made in the image of God and therefore it is his will for me to understand the world and be a steward of it. Just as with the pioneers of modern science it motivates me to seek knowledge about the world and that I have the ability to acquire such knowledge. But my fallibility also challenges me to test my assumptions with empirical methods.

That's why the accuracy of our senses and reasoning is taken for granted.

Yes I agree its appropriate given our experience. However, the question is whether we can assume the reliability of our reasoning, given naturalism. There are several reasons why this is not the case:
1) If naturalism is true, our reasoning has not been selected for truth but for survival. Since the purpose isn’t reliability why would I arbitrarily assume my reasoning is reliable?
2) There are good reasons to think unreliable reasoning could be adaptable

Therefore, it renders such an assumption arbitrary and contrary to the available evidence. Agnosticism about the reliability of our reasoning is a more warranted response to the evidence, if naturalism is true.

[dakoski]

[Replying to post 31 by Divine Insight]

The argument basically sounds to me like he's saying that Naturalism can't explain how humans could have evolved to have reliable cognition since he argues that reliable cognition isn't necessary for survival (a premise that wrongfully assumes that nothing can possibly evolve unless it is absolutely necessary for survival.) I've already explained the amoebas seem to survive quite well. So based on the above premise there would never be any need to evolved above the level of an amoeba. So clearly that premise is already wrong.

I've responded to this already above, do you have any response to my response?

He also seems to be totally ignoring (or refusing to address) the consequences that we should expect if a divine creator had bestowed humans with reliable cognition by purposeful design. If that were the case then why shouldn't we expect all humans to have the same reliable cognition? Why would a divine creator have favored some humans over others?

You keep asserting this would be the case, given theism, but you've not stated why you think this is the case. Could you clarify?

It just seems to me that his reason for dismissing Naturalism is extremely weak, and there is no support for the alternative conclusion that he seems to be drawing.

As far as I can see he's basically doing nothing more than arguing the following:

"I don't understand how evolution works, so I'm going to jump to the conclusion that there must be purposeful design."

But his arguments don't support that conclusion.

I've corrected your misunderstandings in earlier responses which you haven't responded to.

[William]

Is this a question of either/or? Is the argument saying something along the lines of "If there is a creator GOD, then that GOD couldn't have created everything through the device of naturalism?

The OP title certainly gives that impression. ...so the 'Argument Against Naturalism' is more along the lines of the theory of naturalism replacing the idea of a creator GOD?

This extends to the argument "we don't require the idea of a creator GOD because 'naturalism' "

GOD - regardless of any definition - is obsolete in relation to 'naturalism'.?

[Bust Nak]

Its common for atheists to assert that it was arbitrary that modern science emerged in medieval Europe. However...

You have presented a red herring, nothing I said relies on whether Christianity paved the way for modern science or not. The point was people took their senses and reasoning (I am just going to use one to refer to both from here onwards) for granted long before modern science. We have always taken as a first step, the reliability of our senses for granted, before we even try to justify it.

These data raise questions about the validity of arbitrary assertions about the objective validity of reasoning given naturalism.

So some people are less logical than others, perhaps with link to culture, why would that cast any doubt over the validity of logic? Perhaps more to the point, the objective validity of reasoning is taken for granted. You do understand what I am saying here, don't you? You keep asking me to justify my presuppositions, given naturalism. They are called presuppositions because they are pre supposed to be true, naturalism doesn't enter into the picture until we've assumed the accuracy of our senses.

As you’ve not been able to dispute Plantinga’s argument above that if naturalism is true then it’s inscrutable whether our reasoning is reliable since natural selection selects for survival not reliability of reasoning.

Granted, but it's moot since our reasoning is demonstrable reliable, given naturalism, and the presumption that our reasoning are reliable.

There’s evidence that unreliable reasoning can be evolutionary adaptive. Then it’s logically incoherent to go against the evidence and assume our reasoning, if naturalism is true, would be reliable.

But we don't need to go against the evidence because somewhat reliable reasoning is evolutionary adaptive.

You have to first show that you’ve made a logically coherent argument that is consistent with available evidence. If you can’t do that then then parsimony is irrelevant.

But parsimony IS my logically coherent argument for naturalism that is consistent with available evidence.

To make the judgement about whether our reasoning is reliable we have to know
1) something about the origins of our reasoning,

Why do we need to know the origins when we can simply just appeal to our experiences to judge whether our reasoning is reliable?

2) whether our assumptions about our reasoning are coherent with our other assumptions about reality. Such assumptions cannot be arbitrarily asserted within a vacuum.

I can't? Watch me - I assume the accuracy my senses full stop, without appealing to any prior support or premises.

Naturalism builds on top of this presupposition, not the other way round, nor at the same time. As such naturalism is of course coherent with the assumption of accurate senses since it is built to fit around said assumption.

Why? You’ve acknowledged that the reliability of our senses and reasoning given naturalism is simply an arbitrary assumption.

Not quite, I have acknowledged the reliability of our senses is simply an arbitrary assumption. Given naturalism, our senses are demonstrably accurate, we have formal system of logic to verify our reasoning, we have science to verify our senses.

Why would such an arbitrary assumption be objectively true while other equally arbitrary assumptions wrong/incorrect?

By arbitrary assumption I presume you are referring to the presumption of accurate senses. It wouldn't be, hence the word "arbitrary." The other equally arbitrary assumption is simply dismissed out of hand for pragmatic reasons, you need to ground every thought you have on the premise of accurate reasoning.

Again, you’ve misunderstood the question. It’s not whether our reasoning is reliable, given our experience. It’s whether our reasoning is reliable given naturalism. Your response doesn’t answer the latter.

But has the same answer: Our reasoning is reliable, given our experience therefore our reasoning is reliable given naturalism.

Why is presuming the reliability of our reasoning unavoidable?

Because everything is off the table if our reasoning is unreliable. That way lies madness, literally.

Clearly, some naturalists don't find it unavoidable. Including as I quoted above Charles Darwin.

You say clearly, how so? There is nothing to indicated that Darwin is any sort of "reason-solipsist," for lack of a better term.

Are you OK with making arbitrary assumptions that are contrary to current available evidence?

No. That's why I don't making arbitrary assumptions contrary to current available evidence.

The Christian worldview is coherent with my assumption that our reasoning is reliable but fallible. I’m made in the image of God and therefore it is his will for me to understand the world and be a steward of it. Just as with the pioneers of modern science it motivates me to seek knowledge about the world and that I have the ability to acquire such knowledge. But my fallibility also challenges me to test my assumptions with empirical methods.

Hence my point - presuming the reliability of our reasoning unavoidable, you clearly assumed it before you judge the coherency of the Christian worldview. Also, naturalism is coherent with my assumption that our reasoning is reliable but fallible - while unreliable reasoning can be evolutionary adaptive, somewhat reliable reasoning is evolutionary adaptive, as mentioned above.

Yes I agree its appropriate given our experience. However, the question is whether we can assume the reliability of our reasoning, given naturalism...

That's moot since we don't need to assume the reliability of our reasoning, given naturalism; because given naturalism, we can verify the reliability of our reasoning, - re: formal systems of logic and science.

Agnosticism about the reliability of our reasoning is a more warranted response to the evidence, if naturalism is true.

Why would one still be agnostic when our reasoning is demonstrably reliable?

[Divine Insight]

He also seems to be totally ignoring (or refusing to address) the consequences that we should expect if a divine creator had bestowed humans with reliable cognition by purposeful design. If that were the case then why shouldn't we expect all humans to have the same reliable cognition? Why would a divine creator have favored some humans over others?

You keep asserting this would be the case, given theism, but you've not stated why you think this is the case. Could you clarify? .

I don't feel that I need to explain why this should be the case until I hear an argument from the other side for how they can explain that it should be the case.

After all isn't Plantinga's argument based on the idea that human cognition is reliable?

What's he going to do now? Change his argument to be based on the idea that only some humans appear to have reliable cognition?

That would already be a major backslide of his original premise.

His original premise:
Premise 1: The probability of reliable cognition and reasoning is low or uncertain if evolution and naturalism are true.

Look at what's happening here. His original premise was that he suggests that the probability of reliable cognition and reasoning is low or uncertain if evolution and naturalism are true.

And now he's going to take the position that it is indeed low or uncertain because not all humans have reliable cognition and reasoning?

His original premise is already talking on water and sinking. In fact, the moment he concedes that not all humans have reliable cognition and reasoning, then its was already his conclusion that there is a greater probability that evolution and naturalism is true.

So by his own starting premise he can't afford to concede that all humans do not have reliable cognition.

He can hardly continue to argue against his very own starting premise.

So I don't need to offer anything more until he hits the ball out of his side of the court. When he does that, then I can address the apologizes he offers for why his original premise wasn't very concise.

[dakoski]

[Replying to Bust Nak]

I think we’re talking past each other, I’ve probably not communicated what I meant clearly enough. There's also some aspects to your position I'm unclear about.

I get that we need to make presuppositions as starting points for a worldview to get off the ground. Such presuppositions are necessarily circular so we can’t test them directly. However, not all circular arguments are equally valid or useful. I think it is possible, and necessary, to test the validity of our presuppositions. One way of doing that is to examine the logical coherence of these presuppositions – this is what Plantinga’s argument is doing.

I get that you make the presuppositions:
1) our reasoning is valid
2) naturalism is true

What I’m unclear about is whether you are open to examining whether these assumptions are logically coherent. It seems to me, but I may be mistaken, but you seem to be presupposing their logical coherence. I think such an approach is very problematic because essentially you’ve stated that these presuppositions are neither testable directly (which is unsurprising and no problem) nor indirectly (you’re unwilling for their logical coherence to be examined either by empirical evidence or logic).

Alternatively, you could be arguing that on the basis of current evidence and/or logic it is certain that these assumptions (naturalism being true and our reasoning being reliable) are logically coherent. My issue would be how have you come to the conclusion that it is certain that these assumptions are logically coherent?

I’ve given lots of reasons why it isn’t certain these include:
1) the proposed mechanism for the origin of our reasoning, natural selection, does not select for our ability to make logically valid inferences about matters unrelated the environment in which they evolved (e.g. understanding quantum mechanics and solving esoteric mathematical equations).

It selects on the basis of our ability to survive and reproduce. So though it can’t be ruled out that we evolved reliable cognition, if naturalism is true, it can’t be guaranteed either.

2) if you’re a reductive materialist (i.e. all matter is reduced to the physical) then the probability of reliable cognition being adaptive is most probably low. As our behaviour represents conditioned responses to our behaviour – therefore reliable reasoning isn’t needed at all as we don’t have the freedom of will to act according to the conclusions of our inferences. That's not to say its impossible, its just unlikely.

3) There is evidence to suggest that unreliable cognition can be adaptive.

Taken together I don’t think we can conclude that it is certain given naturalism, we have reliable reasoning. Its seems to me it would be highly uncertain, and therefore the most appropriate response to the evidence would be agnosticism about the reliability of our reasoning, given naturalism. Therefore, there is reason to doubt the logical coherence of presupposing these two assumptions.

[dakoski]

Is this a question of either/or? Is the argument saying something along the lines of "If there is a creator GOD, then that GOD couldn't have created everything through the device of naturalism?

The OP title certainly gives that impression. ...so the 'Argument Against Naturalism' is more along the lines of the theory of naturalism replacing the idea of a creator GOD?

This extends to the argument "we don't require the idea of a creator GOD because 'naturalism' "

GOD - regardless of any definition - is obsolete in relation to 'naturalism'.?

Plantinga's argument is that he thinks there is a potential contradiction between two assumptions:
1) Naturalism is true
2) Our reasoning is reliable

Why is that? Because evolutionary fitness is based on the ability to survive and reproduce, not the ability to make logically correct inferences. Its not that its impossible we could not evolve reliable cognition if naturalism is true, its just unclear whether that would be the case.

This is in contrast to other traits that are directly related to our ability to survive and reproduce. For example, no one is going to argue that its logically incoherent to assume a cheetah would have evolved to run fast if naturalism was true. Of course, this is a reasonable assumption.

[dakoski]

He also seems to be totally ignoring (or refusing to address) the consequences that we should expect if a divine creator had bestowed humans with reliable cognition by purposeful design. If that were the case then why shouldn't we expect all humans to have the same reliable cognition? Why would a divine creator have favored some humans over others?

You keep asserting this would be the case, given theism, but you've not stated why you think this is the case. Could you clarify? .

I don't feel that I need to explain why this should be the case until I hear an argument from the other side for how they can explain that it should be the case.

After all isn't Plantinga's argument based on the idea that human cognition is reliable?

What's he going to do now? Change his argument to be based on the idea that only some humans appear to have reliable cognition?

That would already be a major backslide of his original premise.

His original premise:
Premise 1: The probability of reliable cognition and reasoning is low or uncertain if evolution and naturalism are true.

Look at what's happening here. His original premise was that he suggests that the probability of reliable cognition and reasoning is low or uncertain if evolution and naturalism are true.

And now he's going to take the position that it is indeed low or uncertain because not all humans have reliable cognition and reasoning?

His original premise is already talking on water and sinking. In fact, the moment he concedes that not all humans have reliable cognition and reasoning, then its was already his conclusion that there is a greater probability that evolution and naturalism is true.

So by his own starting premise he can't afford to concede that all humans do not have reliable cognition.

He can hardly continue to argue against his very own starting premise.

So I don't need to offer anything more until he hits the ball out of his side of the court. When he does that, then I can address the apologizes he offers for why his original premise wasn't very concise.

Couple of responses:

1) I'm unclear why you keep insisting on this straw man that theism requires all people to have the same level of cognitive abilities - whilst also insisting you don't need to justify why you are asserting this.

2) Plantinga's argument doesn't need to assume our reasoning is reliable. The argument's conclusion is simply that it is logically incoherent to both hold the assumption that naturalism is true and that our reasoning is likely to be reliable.