Using the Applet

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Step 1
We recommend that you leave the box "Blink Conclusion" checked. If you do the conclusion will blink in gold, indicating the way in which an entry for the conclusion would have to look. The button "Random Syllogism" will randomly select a syllogism for you to check if you wish. The button "Random Diagram" will select a diagram. If you wish to see the syllogism associated with that diagram click "Evaluate and Test". We will now explain how to make entries into the applet, supposing that we are evaluating an argument that is already in standard classic form.

All P are M.
Some S are M.
All S are P.


Note that this is a third figure syllogism so click on that in the dropdown for figure. Then enter the premises from the appropriate dropdown. At this point or after constructing your diagram decide whether the argument is valid or invalid.
Step 2
We are now ready to enter the premises in the user diagram. If an area is empty click on the area and it will turn blue (the program diagram will use red for emptiness). If you have an I or O premise you will enter something into one or more of the small circles- this indicates the presence of something. (Mac users "right click" by pressing the mouse button and ctrl at the same time.) Right click to make an entry "x" into a specific area. Note that there are small circles are on boundary line, indicating that we do not know which side of the line the object is. The one we are considering is AIA - 3. Note that you can clear an entry in your diagram by simply repeating the entry operation. Make the entries and then push evaluate and test.

We will do one more syllogism to illustrate a point about I and O conclusions. Do the following one.

All P are M.
Some S are M.
Some S are P.


Note that your entry for the conclusion is in a specific area whereas the blinking conclusion entry is on a boundary. The conclusion is non-committal with respect to the question of whether an S is P is M or not. You have indicated an object which is S and P and M. Since this object is an S which is P the conclusion is indeed true.

You might wish to practice from this page by testing some classic syllogisms for validity.