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Author Topic:   What is Evidence?
Jon
Inactive Member


Message 46 of 51 (544139)
01-24-2010 2:18 AM


Anyone care to participate?


[O]ur tiny half-kilogram rock just compeltely fucked up our starship. - Rahvin
Replies to this message:
 Message 47 by Dr Adequate, posted 01-24-2010 2:42 AM Jon has not yet responded
 Message 49 by MikeDeich, posted 01-24-2010 4:56 PM Jon has not yet responded

  
Dr Adequate
Member
Posts: 16085
Joined: 07-20-2006
Member Rating: 10.0


Message 47 of 51 (544141)
01-24-2010 2:42 AM
Reply to: Message 46 by Jon
01-24-2010 2:18 AM


Anyone care to participate?

Why should anyone care to answer your questions when you're so rude and ungrateful when they do?

You apparently want us to provide you with a free education in epistemology, but without you saying "please" or "thank you".


This message is a reply to:
 Message 46 by Jon, posted 01-24-2010 2:18 AM Jon has not yet responded

  
PaulK
Member
Posts: 14747
Joined: 01-10-2003
Member Rating: 1.8


Message 48 of 51 (544146)
01-24-2010 3:46 AM
Reply to: Message 44 by Jon
01-23-2010 9:55 PM


Premises in Deductive Logic
If you are talking about strict logical arguments, the conclusion is implicit in the premises. That is the conclusion adds nothing - the argument simply brings out what is already there.
All valid logical arguments are tautologous.

And that is how premises support the conclusion.


This message is a reply to:
 Message 44 by Jon, posted 01-23-2010 9:55 PM Jon has responded

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 Message 50 by Jon, posted 01-25-2010 12:35 AM PaulK has responded

    
MikeDeich
Junior Member (Idle past 2633 days)
Posts: 24
From: Rosario, Argentina
Joined: 10-31-2009


Message 49 of 51 (544193)
01-24-2010 4:56 PM
Reply to: Message 46 by Jon
01-24-2010 2:18 AM


Anyone care to participate?

no I don't care to. Ive read this whole thread & you make no sense. What you're trying to argue escapes me & probably other people as well. You are incapable of expressing yourself or your intentions & then you are flippant when people do not respond the way you want.


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 Message 46 by Jon, posted 01-24-2010 2:18 AM Jon has not yet responded

  
Jon
Inactive Member


Message 50 of 51 (544235)
01-25-2010 12:35 AM
Reply to: Message 48 by PaulK
01-24-2010 3:46 AM


Re: Premises in Deductive Logic
If you are talking about strict logical arguments, the conclusion is implicit in the premises. That is the conclusion adds nothing - the argument simply brings out what is already there.
All valid logical arguments are tautologous.

And that is how premises support the conclusion.

Okay. Good. We now have established how premises support their conclusion, but how, then, do they prove their conclusion? I think they can only do this by being proven themselves, which requires something external, no?

If unproven, they still permit a valid argument, and therein lies the problem that I think we need evidence to solve. Without evidence, it seems, there is no way to actually find out whether a valid argument is also sound or whether it is simply just valid. Dr. A. gave a nice example:

Dr. A writes:

Premise 1: If I am an astronaut, then I have red hair.
Premise 2: I am an astronaut.

Conclusion: I have red hair.

This argument is valid and its premises support their conclusion; BUT, they do not prove it, or so it seems to me, because the premises are not proven true, and the argument thus unsound.

How do we prove premises true? Is this the purpose of evidence? If so, how does evidence prove premises true? We are satisfied, I think, with how premises support a conclusionyou laid that out very nicely, thank youbut we still get the problem that a valid argument can have an unproven conclusion if one of its premises is unproven, or correct me if I have erred.

Thank you,
Jon


[O]ur tiny half-kilogram rock just compeltely fucked up our starship. - Rahvin
This message is a reply to:
 Message 48 by PaulK, posted 01-24-2010 3:46 AM PaulK has responded

Replies to this message:
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PaulK
Member
Posts: 14747
Joined: 01-10-2003
Member Rating: 1.8


Message 51 of 51 (544274)
01-25-2010 8:18 AM
Reply to: Message 50 by Jon
01-25-2010 12:35 AM


Re: Premises in Deductive Logic
quote:

Okay. Good. We now have established how premises support their conclusion, but how, then, do they prove their conclusion? I think they can only do this by being proven themselves, which requires something external, no?

Unless you're just proving theorems in an axiomatic system, then ultimately you will have to step outside of deductive logic to find your premises - and demonstrate their proof. So yes the "proof" of the premises will be external to the argument, and will likely involve some other mode of reasoning.

quote:

How do we prove premises true? Is this the purpose of evidence? If so, how does evidence prove premises true?

The study of how we know things - which is really what you are asking about - is called epistemology. If our premises are not derived deductively then they will be supported (if they are supported) by some other mode of thinking, and I cannot think of any I would accept that do not sue some form of evidence.

The details of how that evidence is used, will control how it supports the statement. For instance we could use direct observation to supply a premise for a deductive argument. Or we could use a set of controlled observations to inductively demonstrate a generalised statement.


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