absences of contradictory facts consistent

Two facts that would contradict each other may both be absent. There's no law of the excluded middle in AuthoritySpoke.

authorityspoke/factors.py

@@ -868,7 +868,7 @@ def _contradicts_if_factor(self, other: Factor) -> bool:
 
         if self.absent:
             if other.absent:
-                return other._contradicts_if_present(self)
+                return False
             return other._implies_if_present(self)
         if not other.absent:
             return self._contradicts_if_present(other)

tests/conftest.py

@@ -256,6 +256,7 @@ def watt_factor(make_predicate, make_entity, watt_mentioned) -> Dict[str, Factor
         "f8_higher_int": Fact(p["p8_higher_int"], (0, 2), case_factors=c),
         "f8_int": Fact(p["p8_int"], (0, 2), case_factors=c),
         "f8_less": Fact(p["p8_less"], (0, 2), case_factors=c),
+        "f8_less_absent": Fact(p["p8_less"], (0, 2), absent=True, case_factors=c),
         "f8_meters": Fact(p["p8_meters"], (0, 2), case_factors=c),
         "f9_absent": Fact(p["p9"], absent=True, case_factors=c),
         "f9_absent_miles": Fact(p["p9_miles"], absent=True, case_factors=c),

tests/test_factors.py

@@ -318,6 +318,9 @@ def test_factor_reciprocal_unequal(self, watt_factor):
     def test_factor_different_predicate_truth_unequal(self, watt_factor):
         assert not watt_factor["f7"].means(watt_factor["f7_opposite"])
 
+    def test_unequal_because_one_factor_is_absent(self, watt_factor):
+        assert not watt_factor["f8"].means(watt_factor["f8_absent"])
+
     def test_copies_of_identical_factor(self, make_factor):
         """
         Even if the two factors have different entity markers in self.context_factors,
@@ -420,7 +423,7 @@ def test_equal_factors_not_gt(self, watt_factor):
 
     def test_standard_of_proof_comparison(self, watt_factor):
         f = watt_factor
-        assert f["f2_clear_and_convincing"] >= f["f2_preponderance_of_evidence"]
+        assert f["f2_clear_and_convincing"].implies(f["f2_preponderance_of_evidence"])
         assert f["f2_beyond_reasonable_doubt"] >= f["f2_clear_and_convincing"]
 
     def test_no_implication_between_factors_with_and_without_standards(
@@ -459,6 +462,9 @@ def test_factor_contradiction_absent_predicate(self, watt_factor):
         assert watt_factor["f3"].contradicts(watt_factor["f3_absent"])
         assert watt_factor["f3_absent"].contradicts(watt_factor["f3"])
 
+    def test_two_absences_dont_contradict(self, watt_factor):
+        assert not watt_factor["f8_absent"].contradicts(watt_factor["f8_less_absent"])
+
     def test_factor_no_contradiction_no_truth_value(self, watt_factor):
         assert not watt_factor["f2"].contradicts(watt_factor["f2_no_truth"])
         assert not watt_factor["f2_no_truth"].contradicts(watt_factor["f2_false"])
@@ -564,3 +570,11 @@ def test_check_entity_consistency_type_error(
     ])
     def test_addition(self, make_factor, left, right, expected):
         assert make_factor[left] + make_factor[right] == make_factor[expected]
+
+    def test_add_unrelated_factors(self, make_factor):
+        assert make_factor["f_murder"] + make_factor["f_crime"] is None
+
+    def test_cant_add_enactment_to_fact(self, watt_factor, make_enactment):
+        with pytest.raises(TypeError):
+            print(watt_factor["f3"] + make_enactment["search_clause"])
+