Dignāga's use of the Sanskrit particle eva (only) in his formulation of the third form excludes invalid syllogisms.
Moreover, modern usage distinguishes between valid syllogisms (the conclusions of which follow from their premises) and invalid syllogisms (the conclusions of which do not follow from their premises).
His own exegesis applies a variety of techniques: categorizing genera and species, distinguishing between essential and non-essential qualities, asserting the symmetry of relation, understanding the law of contradiction, recognizing valid and invalid syllogisms, as well as logical fallacies.
In it, she is (or at least was once) widely regarded as having achieved for the first time in history a completely general and unified account of the Aristotelian syllogism, including a general account of the differences between valid and invalid syllogisms.
For trials representing syllogisms that are untrue, valid syllogisms (mismatched syllogisms, untrue-valid) take longer to solve than invalid syllogisms (matched syllogisms, untrue-invalid).
On trials representing syllogisms that are invalid, true syllogisms (mismatched syllogisms, true-invalid) took longer to be solved than untrue syllogisms (matched syllogisms, untrue-invalid).
Thus, for socially anxious individuals, relative poor performance (i.e., slow and more mistakes) is expected when solving SA congruent-invalid and SA non-congruent-valid syllogisms, but relatively good performance (fast and few errors) when answering SA congruent-valid and SA non-congruent-invalid syllogisms.
Furthermore, the dummy for validity is also significant (t (200) = −2.281, p = .012), with SA non-congruent-valid syllogisms being solved slightly faster than SA non-congruent-invalid syllogisms, while the SAcongruency * validity interaction dummy and the SAcongruency dummy are not significant.
2. To get an intuitive idea of why disjunctive syllogism is invalid in paraconsistent logics, think about what we should say about the argument if both Q and ¬Q could be true together.
