- If my mind can play tricks on me, then I don't know that p (where p is a proposition based on a perceptual experience, such as 'This apple is red'.)
- My mind can play tricks on me.
- Therefore, I don't know that p.
- I know that p only if I can rule out the possibility that my mind is playing tricks on me.
- I cannot rule out the possibility that my mind is playing tricks on me.
- Therefore, I don't know that p.
I reject both of the (1)'s. I can know that p even without being 100% certain that p.
ReplyDeleteThanks for your comment, Berry. Why do you think that one can know that p without being certain that p?
DeleteThe argument is valid and it is not sound in that you recognize there is an ability to rule out the possibility that your mind is playing tricks on you because it is not 100%. You assuming that your mind is playing tricks restricts your ability to know P even if it were presented to you accurately. An argument can have a true conclusion but not be valid if the conclusion does not follow logically from the premises of the argument. To say P is unknown seems illogical in that you know P is a variable even if it is not exactly known.
DeleteI believe that neither argument is sound. Both arguments are valid due to the form it is written in, as in if the premises are true then it guarantees the conclusion to be true as well. However, for an argument to be sound, premises must be valid and in fact true. The first argument is not sound because all premises are not true. The first premise of “if my mind can play tricks on me, then I don’t know that p” makes logical sense in reality. For example, if the mind distorts a person’s logic, then certainly the person does not know “p” or the proposition. However, only because the mind can play tricks, it does not necessarily have a direct correlation to the understanding or knowing of p. The use of the word “can” makes a difference in that the mind could have distorted the person’s thoughts, but we do not know if it did. The second argument is not sound, because the first premise does not have to be factually true. We do not need to rule out the possibility of the mind playing tricks for ALL things. The second premise seems to be true as it would be impossible to not rule out that possibility, but the first does not comply with the second.
DeleteIn the first argument, the proposition, p can't be known because the mind is playing tricks. Since the mind is playing tricks, then there is no possible way that p can be known. This argument is valid and sound because the premises guarantee the truth of the conclusion.
ReplyDeleteIn the second argument, the proposition, p, can be known only if it is known that the mind is playing tricks. And since that possibility cannot be ruled out, p is still unknown. This argument is also valid and sound because the truth of the premises guarantee the conclusion.
I agree with these arguments, but I have a couple of additional questions. If our minds can play tricks on us, then how are we able to determine what is true and false based on our perception? How can we trust the perceptions of those who tell us what is supposed to be true? If our minds can play tricks on us, we can never really know what "P" is.
ReplyDeleteExcellent questions, Keith.
DeleteIf these arguments are sound, then we do not have perceptual knowledge. Perceptual knowledge is supposed to be the sort of knowledge (i.e., knowing that p) that is based on what we sense. For example, I see that there is a laptop in front of me right now. But do I *know* that there is a laptop in front of me right now? If the arguments in the blog post are sound, then I do not know that there is a laptop in front of me right now because I cannot rule out the possibility that my mind is playing tricks on me. Perhaps I am just hallucinating that there is a laptop in front of me.
I believe that both arguments are valid and sound. In order for an argument to be sound, it must be valid and it must contain premises that are true. In analyzing the first argument, if the mind can play tricks on you, then you don’t know for certain that a particular object is what it is (P1). Therefore, stating as a known fact that the mind can play tricks on you forms P2. This leads to the logical conclusion that you do not know for certain that an object is what it is (P3). In other words, P1->P2 and P2 ->P3, therefore, P1->P3, which forms a sound argument. The same concept can be applied to the second argument. You can only know for certain that an object is what it is, if and only if you can rule out the possibility that your mind is playing tricks on you (P1). If you cannot rule out that possibility, then that forms P2. This leads to the conclusions that there is a possibility that your mind can play tricks on you and an object might not be what it seems to be (P3). As in the first argument, P1->P2 and P2->P3, therefore, P1->P3, forming a sound argument.
ReplyDelete-Shana J.
After reading the arguments, it can be shown that these arguments are valid. A valid argument would be if the premises were true, then the conclusion would be true too. For an argument to be sound, the premises must be true and therefore making the conclusion true. I don’t think this argument would be considered “sounded”. As long as one premise is false, then the entire argument would be considered “unsound”. In the first argument, the second premise states that “My mind can play tricks on me” but we aren't 100% sure if that’s a true premises. One person can believe that there mind is playing tricks on them, but another person can say that it isn't playing tricks on them. Not only that, but it can just be a perception to the person who thinks that their mind is playing tricks on them. Therefore, I’m not sure if the first argument would be considered a sound argument.
ReplyDeleteFor the second argument, I do think that this is a valid and sound argument. The first and second premises are true, because the argument uses the keyword possibility meaning that it can go either way. Since it is not directing saying that the minds play tricks on us. It is stating the fact that there can be a possibility that our minds are playing tricks on us. This would be considering a true premise because there is a possibility that our mind is playing tricks on us. Therefore, I do think that the second argument would be consider a sound argument.
For the first argument, the argument is sound. For instance, illusions bestow upon the perceiver an assumed result based on patterns or surroundings. An object juxtaposed with larger objects looks smaller than an object juxtaposed with smaller objects. We perceive items in comparison to other items. A color blind person sees gray when the actual object is red. The fact that they perceive the object as gray does not make the object gray. For the second argument, the argument is also sound. Both premise one and premise two are true. The same thing exists in the illusions, even when the objects are compared and then returned to the original state of the illusion, the mind continues to play tricks, making it difficult to rule out the possibility that the mind is playing tricks. Even though the truth is known, the perception remains the same.
ReplyDeleteI find the argument sound which signifies that is valid. Color as we know derives from light. This light goes to the object and then reflects another light that is perceived by our receptors in our vision and send the signal to our brains.
ReplyDeleteThe premises state that without the certainty of knowing how well our mind is or how our brain is perceiving sensation we don't really know for sure if we are certain of p. which concludes that if we do know that our mind can be totally wrong then we don't know p. This also lead us to thinking that we can only know p if we are completely certain that our mind can't make the wrong judgement, however we can't be 100% sure because perception changes, and it can also be influence by our surrounds then the conclusion is right and we don't know p.