What is Accident?

Legal Definition
The informal fallacy of accident (also called destroying the exception or a dicto simpliciter ad dictum secundum quid) is a deductively valid but unsound argument occurring in statistical syllogisms (an argument based on a generalization) when an exception to a rule of thumb is ignored. It is one of the thirteen fallacies originally identified by Aristotle in Sophistical Refutations. The fallacy occurs when one attempts to apply a general rule to an irrelevant situation.

For example:

Cutting people with knives is a crime. →

Surgeons cut people with knives. →

Surgeons are criminals.

It is easy to construct fallacious arguments by applying general statements to specific incidents that are obviously exceptions.

Generalizations that are weak generally have more exceptions (the number of exceptions to the generalization need not be a minority of cases) and vice versa.

This fallacy may occur when we confuse particulars ("some") for categorical statements ("always and everywhere"). It may be encouraged when no qualifying words like "some", "many", "rarely" etc. are used to mark the generalization.

Related inductive fallacies include: overwhelming exception, hasty generalization. See faulty generalization.

The opposing kind of dicto simpliciter fallacy is the converse accident.
-- Wikipedia
Legal Definition
Practice. This term in chancery jurisprudence, signifies such unforeseen events, misfortunes, losses, acts or omissions, as are not the result of any negligence or misconduct in the party. Francis' Max. M. 120, p. 87; 1 Story on Eq. 78. Jeremy defines it as used in courts of equity, to be " an occurrence in relation to a contract, which was not anticipated by the parties, when the same was entered into, and which gives an undue advantage to one of them over the other in a court of law." Jer. on Eq. 358. This definition is objected to, because as accident may arise in relation to other things besides contracts, it is inaccurate in confining accidents to contracts; besides, it does not exclude cases of unanticipated occurrences, resulting from the negligence or misconduct of the party seeking relief. 1 Story on Eq. 78, note 1.

2. In general, courts of equity will relieve a party who cannot obtain justice in consequence of an accident, which will justify the interposition of a court of equity. The jurisdiction being concurrent, will be maintained only, first, when a court of law cannot grant suitable relief; and, secondly, when the party has a conscientious title to relief.

3. Many accidents are redressed in a court of law; as loss of deeds, mistakes in receipts and accounts, wrong payments, death, which makes it impossible to perform a condition literally, and a multitude of other contingencies; and many cannot be redressed even in a court of equity; is if by accident a recovery is ill suffered, a contingent remainder destroyed, or a power of leasing omitted in a family settlement. 3 Bl. Comm. 431. Vide, generally, Com. Dig. Chancery, 3 F 8; 1 Fonb. Eq. B. 1, c. 3, s. 7; Coop. Eq. PI. 129; 1 Chit. Pr. 408; Harr. Ch. Index, h. t.; Dane's Ab. h. t.; Wheat. Dig. 48; Mitf. Pl. Index, h. t.; 1 Madd. Ch. Pr. 23; 10 Mod. R. 1, 3; 3 Chit. Bl. Com. 426, n.
-- Bouviers Law Dictionary
Legal Definition
An unforeseen event, occurring without the will or design of the person whose mere act causes it; an unexpected, unusual or undesigned occurrence; the effect of an unknown cause, or, the cause being known, an unprecedented consequence of it; a casualty. Burkhard v. Travelers' Ins. Co., 102 Pa. 262, 48 Am. Rep. 205; Aetna In Ins. Co. v. Vandecar, 86 Fed. 282, 30 C. C. A. 48; Carnes v. Iowa Traveling Men's Ass'n, 106 Iowa, 281, 76 N. W. 683, 68 Am. St. Rep. 306; Atlanta Acc. Ass in v. Alexander, 104 Ga. 709, 30 S. E. 939. 42 L. R. A. 188; Crutchfield v. Richmond & D. R. Co., 76 N. C. 320; Dozier v. Fidelity & Casualty Co. (O. C.) 46. Fed. 446, 13 In R. A. il4; Fidelity & Casualty Co. v. Johnson, 72 Miss. 333, 17 South. 2, 30 L. R. A. 206.

In its proper use the term excludes negligence; that is, an accident is an event which occurs without the fault, carelessness, or want of proper circumspection of the person affected, or which could not have been avoided by the use of that kind and degree of care necessary to the exigency and in the circumstances in which he was placed. Brown v. Kendall, 6 Cush. (Mass.) 292; United States v. Boyd (C. C.) 45 Fed. 851; Armijo v. Abeytia, 5 N. M. 533, 25 Pan. 777; St Louis, etc., R. Co. v. Barnett, 65 Ark. 255, 45 S. W. 550; Aurora Branch Eh Co., v. Grimes, 13 111. 585. But see Schneider v. Provident L. Ins. Co., 24 Wis. 28, 1 Am. Rep. 157.

In equity practice. Such an unforeseen event, misfortune, loss, act, or omission as is not the result of any negligence or misconduct in the party. Fran. Max. 87; Story, Eq. Jut. § 78. The meaning to be attached to the word "accident," in relation to equitable relief, is any unforeseen and undesigned event, productive of disadvantage. Wharton. An accident relievable in equity is such an occurrence, not the result of negligence or misconduct of the party seeking relief in relation to a contract, as was not anticipated by the parties when the same was entered into, and which gives an undue advantage to one of them over another in a court of law. Code Ga. 1882, § 3112. And see Bostwiek v. Stiles, 35 Conn. 195; Kopper v. Dyer, 59 Vt 477, 9 Atl. 4, 59 Am. Rep. 742; Magann v. Segal, 92 Fed. 252, 34 C. C. A. 323; Bucki, eta, Lumber Co. v. Atlantic Lumber Co.., 116 Fed. 1, 53 C. C. A. 513; Zimmerer v. Fremont Nat. Bank, 59 Neb. 661, 81 N. W. 849; Pickering v. Cassidy, 93 Me. 139, 44 Atl. 683.

In maritime law and marine insurance. "Accidents of navigation" or "accidents of the sea" are such as are peculiar to the sea or to usual navigation or the action of the elements, which do not happen by the intervention of man, and are not to be avoided by the exercise of proper prudence, foresight, and skill. The Miletus, 17 Fed. Cas. 288; The G. R. Booth, 171 In S. 450, 19 Sup. Ct 9, 43 L. Ed. 234; The Cariotta, 5 Fed. Cas. 76; Bazin v. Steamship Co., 2 Fed. Cas. 1,097. See also Perils of the Sea.
-- Black's Law Dictionary
Legal Definition
Held to include the result of human actionable fault or negligence and not synonymous with “purely accidental” or “mere accident.” See 59 Am. St. Rep. 644, 56 L. R. A. 246.
-- Ballentine's Law Dictionary