So, hopefully you're getting a little more comfortable with deductive arguments. To kinda emphasize one of the main points - that TRUE statements don't always guarantee VALID arguments - your short homework assignment tonight is to create three different kinds of argument:
Argument the First. Write a sound deductive argument. (Remember what two features are required to make it sound.)
Argument the Second. Write a valid deductive argument which contains at least one false premise.
Argument the Third. Write an invalid deductive argument with all true sentences (premises and conclusion).
Hint: When writing Arguments the First and the Second, remember that the goal of a deductive argument is to absolutely guarantee that, if someone accepts the premises, s/he is absolutely compelled to accept the conclusion - 0% room for exceptions. You want a totally iron-clad logical connection between your premises and conclusion. (Remember my "Socrates is mortal" example.)
If you found the Venn diagram helpful in visualizing the quarterback-steak argument on the board today, you might find this page (from Washington State University) of interest. It gives several examples of how to evaluate deductive arguments using Venn diagrams (visually), giving you the chance to decide for yourself and then check your answers.
1. If the right side of the above Venn diagram is blue, and the left side is red, and the center is a combination of two sides, and the combination of the colors red and blue is purple, then the center of the Venn diagram must be purple.
ReplyDelete2. If a diamond shaped kite is let go in a gust of wind, and the earth's gravity repels it, then the kite will blow away.
3. If the earth rotates around the sun, and is tilted at 23.5 degrees, then the top layer of the earth's atmosphere is the exosphere.
All I ever wanted to do is be the first to comment. :(
ReplyDeleteI)1.A tree is a plant
2.A plant can't walk.
C.A tree can't walk.
II)1.The Earth is reppeled away from the sun.
2.The sun is pulling Earth with gravity.
C.The Earth and sun will never collide.
III)1.Fish live in water.
2.Humans drink water.
C.Humans drink fish.
I)1. Wood is flammable.
ReplyDelete2. My house is made of wood.
C. My house is flammable.
II)1. All humans have two opposable thumbs.
2. I have two opposable thumbs.
3. I am a human.
III)1. Cars drive on roads.
2. Roads are made of asphalt.
C. Cars drive on asphalt.
A)Plastic is bendable
ReplyDeleteB)My bottle is plastic
C)My bottle is bendable
A)All textbooks have pictures
B)I have a textbook
C)Therefor my textbook has pictures
A)Pens are made for writing
B)Iam writing
C)Therefor Iam using a pen