As related to the LSAT, what is modality?

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  Sami Live Member Sage ⭐ 7Sage Tutor

  December 2016 edited December 2016 10789 karma

  I see modality as the degree of necessity or certainty expressed by a word in a proposition.
  
  For example:
  The word "All" means different in how much quantity is expressed than "some".
  
  Modality could be expressed in quantity as well as probability and possibility.
  So what is expressed by "likely" is different than lets say "rare".
  
  For example if I say "It is likely that the comet will hit the earth therefore the comet will hit the earth". I exceeded the modality of my premise "likely" to conclude "will", which is definite in scope and exceeds what my premise actually allows me to conclude.
  
  Another example is:
  Most of the swans are white, so Swans are white.
  This one is easier to see that I went from "most" to "all" in my modality and exceeded my scope.
  
  So I like to see "modality" on LSAT as the logical force of the argument. And if I exceed my modality from premise to conclusion in any of the stimulus, it is indicative of where the stimulus went wrong logically.
  
  I used to have a list of "modal" words and where each of them stood.
  
  For example, All, 100%, will, every, always, is, are all definite in modality.
  
  But then you have words like likely, most, usually, majority of the time, almost all, which are stronger in force but less than the definite modal force.
  
  And then you have sometimes, few, may, might, could, which are very weak.
• 1 Like

  CinnamonTea Member

  December 2016 550 karma

  Thank you @Sami!
• Sami Live Member Sage ⭐ 7Sage Tutor

  December 2016 10789 karma

  your welcome @CinnamonTea
• 1 Like

  Stevie C Alum Member

  December 2016 645 karma

  Like Sami says, it's about the strength of the claim. None, Some, Most and All are the most common for quantities. For probability, there's "Could occur" "Likely to occur" and "Will occur".
  
  In the context of LSAT prep, it seems that "Modality" is a fancy catch-all term for the varying degrees of quantity (how much?) and probability (how likely?)
  
  For my own clarification, "Few" on the LSAT means "Some but not most", right?
  
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  Q.E.D Alum Member

  December 2016 edited December 2016 556 karma

  Think of modality as the mode of presentation of a proposition. Where the modality is noteworthy, it affects the logical properties of the proposition so that you can't infer what you would normally be able to infer from it.
  
  One logical property commonly obstructed by modality is substitutive identity. Logically, if a and b refer to the same thing, they're identical and you can swap them in any sentence. For example, if Jesse James is Mr. Howard, and someone shot Mr. Howard, then someone shot Jesse James. However, suppose Tim thinks Mr. Howard is an upstanding citizen. Well, that doesn't mean he thinks Jesse James is an upstanding citizen. Maybe he doesn't know they're the same guy.
  
  You can't go from 'Tim thinks(Mr. Howard is an upstanding citizen.)'
  to 'Tim thinks(Jesse James is an upstanding citizen.)'. That's because of the modal presentation of the proposition 'Mr. Howard is an upstanding citizen.', namely the fact that it's presented in the context of "Tim thinks...". That kind of mode is called a propositional attitude, or sometimes a belief ascription. Others include "knows that...", "suspects that...", "laments that..." etc.
  
  I just saw a problem involving propositional attitudes (knowledge) this afternoon, but the most common LSAT probs involving modality seem to be about morals or evaluations. They move from facts to recommendations, like "A and B, so X should C." The "should" context is formally akin to constructions like "It's morally obligatory that X does C" or "It's advisable that C."
  
  Generally (not always), moving between modal and non-modal assertions is suspicious.
  
  Not a big deal, but quantifiers are not modal, though temporal and alethic modalities are often compared to quantifiers. 'All', 'some' and 'most', for example, are classical constants that do not obstruct the logical properties of the sentences they modify. That said, I strongly support the foregoing commentary. @Sami has said about everything that's useful to say about it here.