Common sense should of course be leading in day to day activities. The next time I see a truck coming at me at great speed, I will choose to acknowledge its existence, or I might think myself in intensive care.
You see, the truck doesn’t care whether I am a solipsist or not.
On a more theoretical level though…
The premise that we can’t trust our senses is wrong.
If we can’t trust our senses, then we can’t trust our brain either. After all, the information coming from our senses is registered and processed in the brain.
Why would the processing of sensory data be of any less value than the processing of logical data?
The paradox exists only because we feel that our thought is of a higher level than our senses, which is false.
On the flip side we could ponder what would happen if our sensitory data is correct, but our perception is wrong (actually a much more likely scenario).
In that case, we will never know what hit us.
Sensory data is meaningless if separated from our method of perceiving and interpreting it , so there is no functional difference between the signals coming into our brain omitting the truck, and our brains’ interpretation of the signals omitting the truck. Either way, we won’t know what hit us.
And why should the untrustworthiness of our thought processes contradict the premise that we can’t trust our senses? It’s like they say when somebody wonders whether a person is stupid or merely mistaken: why can’t it be both?
OK, I think you’re right about that. Even if existence caused illusions, you could say that you also know something (in this case the act of existing) is causing the stimuli. Of course, now I’m wondering if you can know more than two things…:smack:
I’m not sure I agree with you on knowing something that is basically imagined. An earlier poster (can’t remember who) made a good point in that the first step in this argument should be to define what it means to “know” something.
Like I said in the above post to Half Man Half Wit, I should have defined “knowing” something first. To me, you know something only when you can prove it in the “real world.” I don’t know an idea because I could always change it, making it into another idea. Technically, nobody really knows how to speak English, because they could always encounter a slang word they’d never heard before. But, like I said, it depends on how you define “know.”
The lovely thing about purely abstract systems like math is that if you can prove them anywhere, you can prove them in “the real world” too - because all the steps of the proof are portable. The definitions of “2”, “4”, etc don’t change whether you’re operating in your head, in a mirage, in a simulation, or the real world - so the proofs based on these definitions work equally well too.
Of course, a relevent question is, is the abstract system in question relevent to the world in question. Sometimes the answer is no - but that doesn’t make the mathematical system invalid, or even necessarily slow us down from using it!
Take, for example, the formula for calculating the circumferance of a circle. C = 2pir. Well, this is all well and good in abstract geometry, where circles are perfectly round. But in the real world, no circles are truly perfectly round. Which technically makes the circumferance formula inapplicable to the “real world”. (Of course, the error of the circumferance formula decreases as the near-circle gets closer and closer to an actual circle, so we use the formula anyway and live with the errors.)
So yeah, sometimes purely abstract systems don’t mesh well with reality - but that doesn’t stop them from being true in those realities, and even useful in some cases.
Here’s another paradox in your system. Suppose you are correct that you can only know one thing, namely that you exist. If you have good reason to believe that you can only know one thing and believe it correctly then by most definitions you know a second thing: that you can only know one thing. In which case, it is false. QED.
You might object that knowing that you can only know one thing is a trivial case that doesn’t really count as knew knowledge. But you have people here who don’t believe that you can know only one thing. If you are correct then you know something they don’t in a meaningful sense, so the proposition You can only know one thing is a non-trivial object of knowledge. And again, necessarily false.
Do I really have to slog through the whole thread to comment? Yeah, since it’s GD? SCREW THAT! It’s all how you operate. Me? I operate as if my perceptions are (mostly) real (an ongoing case of clinical depression leaves a backdoor). Regarding others? I’ve learned that my world is less confusing if I accept them as real, except the obvious bullshit (ie: orbs, poisonous contrails). What others believe? Let them explain it and maybe I’ll listen, at least until I can find a search engine. But I will try to go along, because it’s polite.
IOW, anybody who tries to prove he exists should try to accept that, if he has it together enough to ask, there might be something to it.
IOOW, Dayam! I was a college freshman 36 years ago, but the children of my peers are still asking the same stupid questions! To quote the bygone antidrug ad, “Why do you think they call it dope?”
I know I exist and I know someone else (hypothetically) exists.
I’m me. I’m the guy who will ask such questions as: what if you take it too seriously and “pretend” (notice ‘air-quotes’) that it, whatever it is and whatever is is, isn’t, whatever, eh… ok? … five years later (what is time?) hmmmm…(what does hmmmm mean?) gasp :eek::eek::eek:
I think that the three paragraphs I chose may not have been quite sufficient to illustrate what Chesterton was trying to say about Aquinas. Chesterton’s point was this. First, there is a body of philosophical conclusions that the “man in the street” would recognize as “common sense”. Second, that all the major modern philosophers have reached conclusions that contradict some part of this “common sense”. Third, that Thomas Aquinas was the philosopher who would most closely agree with common sense. However, Aquinas does not argue from common sense. He does not say that certain conclusions must be true because they are part of common sense. Aquinas argued from rational assumptions, using logical deductions. Chesterton’s only point is that the logical conclusions that Aquinas arrives at are common sensical. (I know it’s not a word, but it should be.)
As for what Aquinas’ argument actually is, I’m afraid that I can’t say. I’ve only read small portions of the Summa Theologica, and while I’d like to go deeper at some point, I know that it’s rough going. Based on the summaries I’ve read, it sounds as if Aquinas’ argument may be somewhat similar to the one that Half Man Half Wit is using here, namely starting from the knowledge of the self, one knows that there is a state of existence, and we can expand outwards from there. But really, my only point in posting was to inform you that Aquinas had tackled the issue. I can’t claim to successfully lead you beyond that.
Trying to elaborate a bit further, I don’t think that the argument rests on simplicity or clarity. Rather, it rests only on the existence of a valid set of rules that constitute logic. Now is the existence of such a set of rules in question? Gabba Gabba Hey has gone so far as to question the validity of basic arithmetic in the exterior world. But it’s telling that in his original post, he started by saying “If you really think about it, the only thing you truly know is that you exist.” (Emphasis mine.) So right there, he has admitted that there is such a thing as thought. Moreover, he also seems to acknowledge that some thoughts are valid and other thoughts are not valid.
If we can all agree on that much, then let’s consider what happens if we pursue Gabba Gabba Hey’s line of reasoning. As it happens, this was a topic that Chesterton took on himself in a chapter of Orthodoxy called The Suicide of Thought. The conclusion is summarized in the title. If a person insists on being so totally so totally reductive–as Gabba is–then eventually the line of reasoning recoils and destroys itself. How could he even know that he only knows of his own existence, if he won’t accept some thoughts as absolutely valid?
I don’t think that’s particularly telling; i’m not a huge fan of wording “gotchas”, since generally we’re not exactly hugely accurate when we use language. I would prefer to use “with the appearance of thought, the only thing…” and even that i’d question, since while it was true for me once it not longer is (i’ve already had that appearance, after all) and for others it may take shorter or longer to catch onto the idea.
I do question the existence of basic rules of logic, both that they exist at all and that they exist as we know them. We can’t know they exist, because if they don’t, then it’s quite possible our tools to know this will return incorrect results. You can’t measure the accuracy of a ruler with the ruler itself.
The line of reasoning doesn’t destroy itself - rather, it may destroy itself, but like everything else, we simply do not know. I don’t believe we know we exist, again either totally or as we believe ourselves to be. To take one example, you believe in free will, I believe, whilst I do not; one of us is incorrect in our knowledge of ourselves, if our understanding of logic is correct or is wrong but happens to return that result anyway.
I accept no thoughts as absolutely valid. To the extent that I accept relative validity, it is because it appears at least to keep up with appearances, but as shown, appearances vary wildly between different people (if there are different people, or people at all ;)), so even that is entirely personal, if there is a me for it to be personal for. Everything is questionable; there are no certainties, except of course that there might be.
It’s all how you operate. Me? I operate as if my perceptions are (mostly) real (an ongoing case of clinical depression leaves a backdoor). Regarding others? I’ve learned that my world is less confusing if I accept them as real, except the obvious bullshit (ie: orbs, poisonous contrails). What others believe? Let them explain it and maybe I’ll listen, at least until I can find a search engine. But I will try to go along, because it’s polite.
… five years later (what is time?)