Forums → WEPR → Why do we presuppose what we do?

I suppose presupposition comes from experience. Gravity for example. We cannot "see" it in a sense, but we experience its effects. So in the same sense, we presuppose that the world is real partly because of the fact it "feels" real. The rest come from our life experience.

Here's an example from "The Little Prince": When he was young, the pilot drew an elephant inside a snake. But the way it was drawn, it looked like a hat. So, from experience, everyone assumed it was a hat.

Of course that's not presupposition, merely incorrect assumptions (since they didn't take for granted that the drawing depicted a hat, just assumed it). But I believe it happened for the same reason.

For the brain in vats thing, it is fairly simple in my opinion. When you're born, you have pretty much no notion of illusion and no idea what a brain is. Why would you presuppose anything other than that this is reality?

For the rest, I agree with Doombreed on the role of experience.

Why do we presuppose? Doombread and HahiHa said it allready and I agree wih em. It feels and it is more logically to explain. If we weren't reall why would I have this strange dream (or what ever)? And why would I made you in it to ask me that question? And why do I dream then?

This is so weird - I'm working on a paper right now that deals with when (and whether) presuppositions are justified, though I don't really address the 'why' question in the paper.

Just to be clear, the key feature of a presupposition is something called projection. A proposition is projected if it is implied by the truth of some other proposition. The classic example here goes like this:

(1) If the king has a son, then the king's son is bald.

Putting aside worries about definite descriptions, (1) presupposes that there is a king. But it doesn't presuppose that the king has a son.

At any rate, what Mage is talking about here is what we might call (for lack of a better term) global projection. In the example above, the presupposition was pretty specific. But notice that by typing (1) - and this entire post - I'm presupposing that the reader can read and understand English. And by typing that previous sentence, I'm presupposing that someone will actually be reading this at some point.

But what we're talking about is much, much broader. Behind all of this seems to be the presupposition that the world is pretty much how we perceive it to be. Science needs this presupposition to even get off the ground. But for the rest of us, what's going on here?

I think the previous posts pretty much sum up the 'why' part of the question. Evolutionarily, it would seem that we're much better off presupposing that the world is pretty much how we perceive it to be. But evolutionary processes like this are matters of expedience - an organism is just better suited for survival with certain features rather than others. And it seems like this kind of presupposition falls within that explanation.

But the natural line to take here is that expedience doesn't imply truth (unless you're a hardcore pragmatist or something). In other words, our faculties of perception and rationality can be deceived, so what is justifying this global presupposition?

My answer to this question is that nothing does. It's not justified - it can't be. But, because I'm a safety theorist and a neo-Moorean, it's still something that we can know.

So here are some questions that are involved in this global presupposition/projection (GP):

1) Is GP justified, and does it need to be?
2) Do we need to know whether the GP relationship holds?
3) Is GP, in fact, even a presupposition that's in play?

Having presuppositions come from experience would sound like a good reason though for that we would have to make presuppositions about those experiences or even having experiences in the first place.

Could it be the two have to in a way go hand in hand, one supporting the other?

To give a bit more clear view of where my mindset was at the time the question of why presuppose was raised. The apologist was in the "how do you know, how do you know... etc. etc." cycle of how do we know our reasoning is valid. I would say we valid our reasoning through evidence, our existing information. The apologist then of course pointed out that aren't we using our reasoning to as they put it "deduce our facts" in the first place.

Setting aside that I think what the apologist did was essentially change his initial question from validation to use, that kind of plays a role in what I mean about having things go hand in hand.

But notice that by typing (1) - and this entire post - I'm presupposing that the reader can read and understand English. And by typing that previous sentence, I'm presupposing that someone will actually be reading this at some point.

Interesting you would point that out. I was doing a bit of reading on a site before making this post that used a similar example.

I think the previous posts pretty much sum up the 'why' part of the question. Evolutionarily, it would seem that we're much better off presupposing that the world is pretty much how we perceive it to be. But evolutionary processes like this are matters of expedience - an organism is just better suited for survival with certain features rather than others. And it seems like this kind of presupposition falls within that explanation.

This is kind of why I think there may be some utility involved in holding a proper presupposition and perhaps that might play a role in why we would hold it.

Like with my example of presupposing the world around me is real, that has the utility of playing to my survival. This point wouldn't have to cover just survival either. For instance there was utility in presupposing there was a reader and that reader could understand English in the form of taking action to communicate in the first place using English.

My answer to this question is that nothing does. It's not justified - it can't be. But, because I'm a safety theorist and a neo-Moorean, it's still something that we can know.

Could you expand a bit on why you think it can't be justified and why you think this isn't a problem?

1) Is GP justified, and does it need to be?

I suppose (pun?) that I've given one possible justification in the from of utility.

Interesting you would point that out. I was doing a bit of reading on a site before making this post that used a similar example.

I might have inadvertently stolen that example from somewhere. We probably read the same things (e.g. the SEP article) as I didn't know anything about presuppositions before I started working on this paper

Could you expand a bit on why you think it can't be justified and why you think this isn't a problem?

Sure, though it's going to go wildly off topic - at least in a sense. I mean, your OP deals with scepticism, so it's not that crazy off topic.

But anyway, like I said I'm a neo-Moorean safety theoriest. The neo-Moorean means that I follow in the footsteps of G.E. Moore and claim that we can know the negation of sceptical hypothesis. In other words, we can know that we're not brains-in-vats. The safety theorist part explains how this is so.

Safety is a constraint on knowledge - it's what I (and others) call an anti-luck condition. We don't want beliefs that are only luckily true to count as knowledge, and this is where safety comes in. A belief is safe if and only if the belief couldn't easily have been false. This is a modal notion, meaning we look at nearby possible worlds to determine whether the belief is safe or not. If the belief is false in most or all of those nearby worlds, then it could have easily been false - and thus unsafe (so it wouldn't be in the market for knowledge).

But if the world is pretty much how it appears to be, then a world in which we're BIVs is very, very remote. In other words, it would be radically different from the actual world. In that case, our belief that we aren't being radically deceived would count as knowledge. After all, it's safe and it meets other requirements for knowledge.

The problem here is that belief can't be justified - I mean, how could it? In other words, we don't have any reason to think that belief is true (this is a very broad notion of justification). Some people find this a really unsatisfying answer to the sceptical challenge for knowledge. But I argue that these people don't properly understand the challenge. (I won't go into detail here, but feel free to ask me on my profile or create a separate thread on scepticism if you want.) This does create a bit of a worry, though - which is cashed out in the notion of epistemic angst. Basically, it's the conjunction of a piece of knowledge without any sort of reason for believing this piece of knowledge - i.e., that we're not being radically deceived.

I don't see this as a genuine problem, though - at least for an account of knowledge. Epistemic angst turns out to be a pretty common phenomenon that presents in a variety of ways. The sceptical challenge is special, to be fair, but it's a theoretical constraint on an account of knowledge - not a genuine epistemic concern.

I suppose (pun?) that I've given one possible justification in the from of utility.

This ties into the (broadly) pragmatist theory of truth. What is true is what is expedient to believe. Sounds like you want to move this notion back, though, and say that what is justified is what is expedient to belief. I'll need to have a think about that, but since I'm not sure I'm even representing your position accurately, I'll let you fill in the details before I respond.

I think Doombread answered this pretty fully. It's based on our life experiences. If I look at a tree, I can automatically assume it contains wood.
What's more interesting is the presupposition of knowledge at birth. For example, babies, when they are born know how to suckle, cry, breathe and defecate (and let's face it, that's ALL they do). Babes have that innate knowledge without any coaching or teaching. We can apply this to later stages in life. I think that pre-supposition comes from how we are brought up as people. If one kid is brought up Christian all his life, he will presuppose that there is a God. If another kid is brought up atheist, the will presuppose the opposite. In the teen years, this changes, though, as their own ideas start to form. The breakdown of presupposition happens when ideas are challenged. I never second -guessed my concept of reality until I took a philosophy class in college, for example.

The problem here is that belief can't be justified - I mean, how could it?

It sounds to me like meeting the requirement of being safe could be a form of justification.

This ties into the (broadly) pragmatist theory of truth. What is true is what is expedient to believe. Sounds like you want to move this notion back, though, and say that what is justified is what is expedient to belief. I'll need to have a think about that, but since I'm not sure I'm even representing your position accurately, I'll let you fill in the details before I respond.

Yes that sounds about right for what I'm saying.

I think Doombread answered this pretty fully. It's based on our life experiences. If I look at a tree, I can automatically assume it contains wood.

But again doesn't that require us to form presuppositions about the experiences?

Safety is a constraint on knowledge - it's what I (and others) call an anti-luck condition. We don't want beliefs that are only luckily true to count as knowledge, and this is where safety comes in. A belief is safe if and only if the belief couldn't easily have been false. This is a modal notion, meaning we look at nearby possible worlds to determine whether the belief is safe or not. If the belief is false in most or all of those nearby worlds, then it could have easily been false - and thus unsafe (so it wouldn't be in the market for knowledge).

Would be off topic here, but that would be interesting to see applied to religious beliefs.

It sounds to me like meeting the requirement of being safe could be a form of justification.

You're right - it is a kind of justification. But it's a completely externalist one, meaning that whether a belief is justified does not depend on the epistemic state of the agent. Instead, it depends on the world around her.

When we think about justification, we tend to think of it along internalist lines - i.e. reasons that you have that support the truth of your beliefs. I believe that Obama is in such-and-such a place because I saw it on the news. This is a reason that I have and one that I have access to. It doesn't work like that with safety.

You might say that knowing whether a belief is safe *is* something to which we can have access. This ties in to why, when we want directions (for example), we consult a map and not a Ouija board. Maps give us safe beliefs about which direction to go whereas Ouija boards don't. So in this way, maybe we do have access to whether or not the beliefs are safe.

There are 2 responses here. The first is that we've changed the claim on offer. It's no longer whether the belief is safe but whether we have good reason to think the belief is safe. Making this move allows for safety and justification to come apart in both directions. I might think a belief is safe when it isn't; or a belief might be safe but I don't think it is. So we've gotten the internalist flavour, but lost the core notion of safety in the process.

The second response is that, in cases of radical scepticism, we can't have access to whether the belief is safe or not. This is built into the question raised by sceptical hypotheses. G.E. Moore famously said he could be internally justified - and thus know - that we're not being radically deceived. His method was literally "Here's one hand, and here's another". In other words, all of the evidence around him points to this being the actual world. There is no evidence whatsoever that we're being radically deceived. But even a faithful neo-Moorean such as myself is going to recognise this as a terrible move. At best, it's question-begging. At worst, Moore has completely misunderstood the sceptical challenge to knowledge.

Yes that sounds about right for what I'm saying.

That's a very interesting move. I'm not familiar with anyone who makes this sort of move, but there might be a very good reason as to why -- loads and loads of couterexamples.

Let's say I'm at a fork in the road on my way to Athens and I don't know which way to go. I would definitely be justified if I looked at a correct map and formed the belief that I should take the left path. But suppose I don't have a map, so instead I flip a coin. It would be expedient for me to believe the outcome of the coin toss - say, heads I go left and tails I go right. After all, I don't have a map and I've got to make a decision. But the intuition here is that my belief about which way to go isn't going to be justified - even if I wind up with a true belief.

I'll need to think more about this, though. There's another feature of belief that has to do with transparency that might be telling here. But I can't get my head around the relationship right now.

Would be off topic here, but that would be interesting to see applied to religious beliefs.

As a quick note, if God does exist, then God exists necessarily. So a belief in the existence of God would be safe if God does exist. Of course, that's just theistic belief and not religious belief. And it's also about as helpful as our beliefs that we're not being radically deceived.

Let's say I'm at a fork in the road on my way to Athens and I don't know which way to go. I would definitely be justified if I looked at a correct map and formed the belief that I should take the left path. But suppose I don't have a map, so instead I flip a coin. It would be expedient for me to believe the outcome of the coin toss - say, heads I go left and tails I go right. After all, I don't have a map and I've got to make a decision. But the intuition here is that my belief about which way to go isn't going to be justified - even if I wind up with a true belief.

In that example, don't think I would be thinking the coin flip got it right. my belief in this case would be I only have two options leaving me with a 50/50 chance of getting it right and going with the coin flip would be no better than going against it.

In that example, don't think I would be thinking the coin flip got it right.

You're absolutely right on that one; I can see wanting to cash out this case in this way. But remember the claim on offer - that we are justified in believing what is useful/expedient to believe. This analysis would mean that we are justified in believing whatever the outcome of the coin toss is.

But there are cases in which your account might get things right. Say I'm on the roof of a building that's on fire and my only means of escape is to jump across a very wide gap to the rooftop of the adjacent building. It would be really useful for me to believe that I can make this jump. After all, if I'm confident in my jumping abilities, I'm more likely to make the jump and not freak out and fall right before I jump. And there's an intuition here that I'm justified in believing this. But here's a really interesting point that comes up. My reasons for believing I can make the jump aren't epistemic reasons - they're pragmatic reasons.

This speaks to a much broader point about this way of approaching justification. Being justified in believing that P involves having reasons for believing that P. The standard line, though, is that our reasons should be epistemic. As an analogue, consider making a moral decision - say whether to fulfil my duty as a soldier and go to war or fulfil my duty as a son and stay home to take care of my sick mother. Whatever decision I make is going to be based on reasons - in this case, moral reasons. So the thought here is what makes epistemic choices behave differently from reasons in other realms. After all, if justification is just what is expedient to believe, then any time I'm justified is going to come down to pragmatic reasons rather than epistemic or alethic (truth-related) ones.

This ties into my earlier point regarding transparency. There's a very pervasive thought that when we considering whether to believe that P, we are thereby considering whether P is true. In fact, the thought here is that truth considerations are completely transparent in the question of whether to believe that P.

But what does this have to do with the question? Well, notice that when we presuppose something, transparency seems to be right there. In other words, by presupposing that P we are thereby assuming that P is true. And the intuition is that, if this presupposition is justified, then it's going to come down to epistemic reasons. The problem is that, when we think about radical scepticism, whatever is justifying our belief that we aren't being deceived isn't going to be an epistemic reason. If I'm a safety theorist, for example, it's going to be reasons that are completely external to me. If I do have any internal reasons, they're going to be more philosophical than epistemic (i.e. I believe that safety theory is the correct response to radical scepticism).

This actually puts you in a really interesting position. Notice that I'm going to have epistemic reasons for lots of ordinary beliefs, but when it comes down to radical scepticism, by reasons change to philosophical ones. But for your approach, it's pragmatic reasons all the way down. And this seems to be the best way of capturing the intuition that's on offer in this thread - presupposing that the world is pretty much how we perceive it seems to be a matter of expedience. Of course, the trade-off is getting our ordinary everyday beliefs a bit wrong. But maybe this is how justification works in presupposition, but not belief?