ATAR Notes: Forum
Uni Stuff => Universities - Victoria => Monash University => Topic started by: notguilty on October 06, 2014, 11:36:49 pm
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Hey guys,
Is this logically correct: if A causes B and A is rational then B must also be rational?
If so, is there a formal name for it that I can look into further? (This is for uni, I'm not trying to get all philosophical hahahaha)
Thank you!
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Not sure what exactly you mean by 'logically correct'. The two terms that we use to describe an argument are: valid and sound. An argument is valid if there are no issues with the structure of the argument, and the conclusion must follow from the stated premises. An argument is sound if, in addition to being valid, each premise contained with the argument is true, so that the conclusion is true. Note that a valid argument need not be sound. ('P1. If Melbourne is in China, then it is also in Asia. P2. Melbourne is in China. C. Therefore, Melbourne is in Asia.' constitutes a perfectly valid argument, since the conclusion follows from the premises, but the argument is by no means sound, since, although P1 is true, P2 is not, so the conclusion is not true.) However, a sound argument must be valid.
I may be misinterpreting your argument, but the argument that you presented above seems neither valid nor true. If you cause the keys on a keyboard to move, and you are rational, does it automatically follow that the event of 'keys on a keyboard moving' is rational? By the looks of things, A seems to be an autonomous agent, e.g. human, but B seems to be an event. An event, in general cannot be rational.
What you are after may be the following. There are four common argument structures that philosophers often invoke.
P1. If P, then Q.
P2. P.
C. Therefore, Q.
This is called modus ponens. It is not hard to see that modus ponens constitutes a valid argument. If Melbourne is in Victoria, then it is in Australia. Melbourne is in Victoria, therefore Melbourne is in Australia. No issues there.
P1. If P, then Q.
P2. Not Q.
P2. Therefore, not P.
This is called modus tollens. This also constitutes a valid argument, and mathematicians like to invoke this kind of logic when constructing a proof by contrapositive. If Melbourne is in Guangdong, then it is in China. Melbourne is not in China. Therefore, Melbourne is not in Guangdong. Again, no issues there.
P1. If P, then Q.
P2. Q.
P3. Therefore, P.
This is called affirming the consequent. This does not constitute a valid argument. It is easy to see why: If Melbourne is in NSW, then it is in Australia. Melbourne is in Australia. Therefore, it is in NSW. True? Certainly not.
P1. If P, then Q.
P2. Not P.
C. Therefore, not Q.
This is called denying the antecedent. Such arguments are also no good. If Melbourne is in NSW, it is in Australia. Melbourne is not in NSW. Therefore, it is not in Australia. True? Again, certainly not!
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Hey guys,
Is this logically correct: if A causes B and A is rational then B must also be rational?
If so, is there a formal name for it that I can look into further? (This is for uni, I'm not trying to get all philosophical hahahaha)
Thank you!
Brightsky's on the money.
Look up syllogistics with reference to determinism. I think there was a whole Stoic argument about rational determinism. For Stoic determinism look up Susanne Bobzien's work. Also look up the concept of rational agency.
(This is from a review of a journal article, I think the end bit is somewhat relevant)"Epicurus does go on to reject determinism because of the threat it poses to rational agency; he was worried, according to O’Keefe, about the fatalism which he thought results from logical determinism, in the form of the Principle of Bivalence, according to which every proposition, even propositions about the future, is either true or false. Thus, O’Keefe stresses the parallels between Aristotle’s discussion of bivalence in De Interpretatione, 9 and Cicero’s discussion of Epicurus in his De fato. Epicurus thought that the Principle of Bivalence implies, given an Interentailment Thesis—namely, a bridge thesis between logical and causal determinism—that future propositions are true, and true in virtue of some facts about the present that are sufficient conditions for that future proposition’s being true. Hence, there are facts now that are sufficient to make that future proposition true. But this implies fatalism: our decisions will not make any difference to what happens, we will not be genuine causes of what happens, and our reasoning will not be causally efficacious (see chapter 3 for discussion of what it is for an agent to be a genuine archę or “origin” of action). Fatalism is incompatible with rational agency and control."