Common Sense and Logic: What's the Difference?

[ocean09]

What is common sense?
Is it synonymous with logic?

 

[HallsofIvy]

Common sense is far from being "synonomous with logic". For one thing, it is not well defined. Many people use "common sense" to mean prejudice based on one's prior experiences. Of course, individual experiences may not reflect overall reality. It is not uncommon for the result of logic or experiment to appear to contradict "common sense".

 

[loseyourname]

Historically speaking, "common sense" philosophy owes its contemporary formulation to G.E. Moore:

An important aspect of Moore's rejection of idealism was his affirmation of a ‘common sense’ realist position, according to which our ordinary common-sense view of the world is largely correct. Moore first explicitly championed this position in his 1910-11 lectures Some Main Problems of Philosophybut he made it his own when he responded in 1925 to an invitation to describe his ‘philosophical position’ by setting this out as ‘A Defence of Common Sense’. Moore begins the paper by listing a large number of ‘truisms’ such as that ‘the Earth had existed also for many years before my body was born’. Concerning these truisms he then asserts, first, that he knows them for certain, second, that other people likewise know for certain the truth of comparable truisms about themselves and, third, that he knows this second general truth (and, by implication, others do too). So the truth and general knowledge of these truisms is a matter of common sense. Having set out these truisms, Moore then acknowledges that some philosophers have denied their truth or, more commonly, denied our knowledge of them (even though, according to Moore, they also know them) and he attempts to show that these denials are incoherent or unwarranted. These claims might seem to leave little space for radical philosophical argument. But in the last part of the paper Moore argues that his defence of common sense leaves completely undecided the question as to how the truistic propositions which make up the common sense view of the world are to be analysed; the analysis may be as radical as one likes as long as it is consistent with the truth and knowability of the propositions analysed. Thus, for example, he is content to allow that philosophical argument may show that a phenomenalist analysis of propositions about the physical world is correct.

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"Logic," on the other hand, comes all the way down from Aristotle's principle of noncontradiction and owes its contemporary development largely to Boole, Frege, and Russell, who made it symbolic and mathematical.

The major difference between the two is that common sense deals with trivially obvious truisms about the empirical world that are independent of the existence of minds. Logic, on the other hand, deals with the "laws of thought," or modes of proper reasoning, which are entirely in the mind. Rather than dealing with the empirical truth of propositions about the empirical world, logic only deals with the truth of compound sentences given the truth of its atomic components. In the cases of tautologies and contradictions, the truth of sentences follows necessarily from structure and is not dependent upon the truth value of atomic components, but 'truth' in this case still owes nothing to the empirical truisms of common sense statements; rather, the logical notion of 'truth' is purely mathematical or functional. It is a value assigned by the creators of systems of logic, not dictated by the empirical world. This distinction in known historically as the "analytic/synthetic" distinction.

 

[Pythagorean]

Einstein said:

Common sense is the collection of prejudices acquired by age eighteen

 

[Andre]

So what was once common sense in historical perspective?

The Earth is flat

The Earth is at the centre of the universe

http://www.happylanding.com/MWNF.htm

Hmm perhaps that the worst enemy of progression of science is common sense.

 

[AO eye 5]

"Common" sense (sensory/experience) & dominant effects.

Hi everyone,

This is a very interesting question regarding something that is done without much identification. Aside from my lack of philosophical background, I want to contribute to this thread the interaction of the signifier and processual cultural practices such as the datum along with the nature of knowledge itself.
It has been a pain to find sufficient literature regarding the use of the signifier outside of the trivial, but I have vicarious observation of sense through a person I know who frequently watched CNN headline news who was rudely interrupted by a common sense advocating person on the channel (roughly a year ago, significant because I do not own a tv). Common sense defined in this manner, or more properly identified, also defines issues as morality, heirarchy, and the establishment of "rights." Knowledge, through a new standard, sidesteps the discourse of learning in a kind of socialized consent which is vaguely termed "common sense."

I hope this adds to the thread, I wish to participate in the philosophy forums.

 

[0rthodontist]

Ocean, are you referring to so-called "common sense" expert inference systems such as Cyc?
http://www.google.com/search?hl=en&q=cyc&btnG=Google+Search
My personal belief is that expert systems act in a way very different from the human brain, although they can be good tools for particular problems. One reason is that if the mind really did operate like that, everyone would be fantastically good at logic puzzles. The toughest Sudoku would take us seconds.

 

[moving finger]

The major difference between the two is that common sense deals with trivially obvious truisms about the empirical world that are independent of the existence of minds.

I would tend to disagree. I think the "common" definition of common sense is based more on accumulated "wisdom" and understanding gained through pre-philosophical intuition and experience (hence is more in line with the posts of Pythagorean and Andre) - thus not only is common sense very much a product of the existence of minds but common sense also is very often a reflection of intuitive prejudice rather than a reflection of any truisms about the empirical world.

Our "common sense" often rebels against some of the implications of relativity and quantum mechanics - which is why so many people have problems accepting the implications of these fields of scientific endeavour.

"Common sense" also tells many of us that we act as free (autonomous) agents with ultimate responsibility for our actions...

Best Regards

 

[Mickey]

G.K. Chesterton made a living writing about common sense, since he perceived that common sense was no longer common. He's also one of the most prolific writers in human existence, producing "around 80 books, several hundred poems, some 200 short stories, 4000 essays and several plays," according to Wikipedia. I think you'd find some of it interesting.