Ought we, though? Truly? Now it seems you're smuggling in agency where it needn't be. Sometimes it is beneficial to believe things that aren't true (type A cognition errors for example), just as there are things that are harmful to believe are true, yet we survive and reproduce just fine. Rather than say that we ought or ought not grasp something as true, I'd probably say that we either do so, or fail to do so.
But are our cognitive faculties not generally
reliable for producing true beliefs? Reliability is normative--we rely on our belief-forming structures to form true beliefs because we take it that that's what they're
supposed to do, as their
function, not because we take it that that's what they just
happen to have done in the past. If that's not what they're
supposed to do, then why continue to rely on them to give us true (or at least mostly true) beliefs?
And I fail to see how grasping the validity of things like axioms and logical syllogisms could not possibly come about from an evolved, functioning brain.
Because evolution is
essentially a mechanistic process. It
essentially builds 'machines' that preserve and replicate themselves, in that
preservation and
replication of individual organisms are
the two fundamental principles underlying
all evolutionary processes. All evolution 'cares' about (please pardon the anthropomorphic language, but it's the best way I know to make my point) are the mechanisms that cause organisms to survive and replicate themselves. Strictly insofar as a brain is a proper component of a 'machine' that has been built according to evolutionary processes, its functionality must derive from the fundamental principles that guide those processes. Thus, the evolutionary answer to the question of why we have
any organs that function the way they do essentially boils down to this: Our ancestors' having those organs with those functions is what enabled them to survive and reproduce.
From an evolutionary perspective, the reason why we have brains that work the way they do is because our ancestors' having brains that worked that way is what enabled them to survive and pass on their genes to us. But having beliefs that are true is irrelevant to the evolutionary 'concerns' of physically getting an organism's body parts to where they need to be in order for that organism to survive and reproduce. If causal processes involving wildly false beliefs, or no beliefs at all, would get the job done more efficiently than those involving true beliefs, then evolution would 'gladly' cast off true-belief-forming structures as garbage in favor of whatever works better.
This is why I say that naturalistic evolution--i.e. evolution strictly via blind mechanistic causation operating on random variation--is fundamentally incapable of producing belief-forming structures as selective adaptations
insofar as those belief-forming structures produce beliefs that are
true. Evolution doesn't 'care' about what's true; all it 'cares' about--indeed, all it
can 'care' about--is what works according to its 'purposes' of preservation (survival) and reproduction.
True beliefs would be an evolutionary afterthought, and so they can't be a proper function according to an evolutionary paradigm.
Mmmm.... okay, accept. I don't know why I feel the weight of some unnecessary baggage, but... accept.
Well, I can think of a couple of points you might like to consider:
How might we go about explaining
truth as some sort of actual entity that can actually
cause mental states to occur in explanatory terms that do not invoke, or presuppose, the very truth we're trying to explain? In other words, how could we explanatorily reduce, or break down, truth itself into simpler terms, while at the same time preserving both it and its causal power (i.e. so that it can still, somehow, properly be said to exist and cause, and not be entirely illusory)? If we can't do this, then I don't see any way that we can preserve
physicalism.
Can truth (or a true proposition, if you will)
by itself be
sufficient to cause the formation of a true belief? Doesn't there need to be a mind to be able to grasp it? And if grasping truth is a capacity that minds inherently have as part of their essential nature (i.e. as per what it is to be a mind), then might we not say that, in some sense, grasping truth is what minds are
for?
You'll have to define the term proper, and demonstrate its distinction from currently evolved. I now can't help but see your posts through the lens of agency attribution, and you seem to have this idea that this was always the end goal of the brain. Our brains are still evolving, just as they are quite a bit more evolved than they were 250,000 years ago when we were a different species.
I might need to expand on this later, but for right now, let's define a function of some entity as
proper if it is an activity of that entity that is in accordance with some intelligible principle by which the entity itself is causally explained. This principle needn't have been
literally designed in the entity by some rational agent in order to satisfy this definition. It might very well have formed the entity via entirely natural (non-agentive) processes. What's important is simply that there
be an intelligible modus operandi at work in the entity's functioning that reflects its causal origins.
I don't think I'm a fan of the term evolution does or doesn't care, so if you don't mind, I'll rephrase it: While it's true that natural selection rewards utility and reproduction, the beings that successfully reproduce do care about things being true. At least the ones who survive seem to have a better grasp of reality than the ones who do not survive. In that sense natural selection does reward the truth of a proposition through the species who tend to grasp that truth.
But when all is said and done, they survive, not because what they believe is true, but because whatever causal processes are at work in their behaviors get the job done in terms of survival and reproduction. You are right, of course, that some organisms (we humans at least) do
tend to care about truth, but this doesn't mean that we actually
get truth from our belief-forming structures. The carrot of truth that natural selection holds before our eyes might be nothing more than a hologram put there in order to get us to go through the right motions. Of course, I don't believe that it
is a hologram. I believe that we really can acquire truth. But in order to do this, I must believe that our minds are reliable for producing beliefs that are actually true, and this requires that I believe that acquiring truth is what our minds are properly
for.