Depending on breed, management and environment, the domestic horse (including draft horses) today has a life expectancy of 25 to 35 years. It is uncommon, but a few animals live into their 40s and, occasionally, beyond. The oldest verifiable record was Old Billy, a 19th-century horse that lived to the age of 62.
TRUE. Validity is a necessary condition for being sound. 14. FALSE. A valid argument can have a true conclusion and false premises (see #11); and if an argument does not have all true premises, then it is not sound.
A deductive argument is said to be valid when the inference from premises to conclusion is perfect. Here are two equivalent ways of stating that standard: If the premises of a valid argument are true, then its conclusion must also be true. It is impossible for the conclusion of a valid argument to be false while its premises are true. (Considering the premises as a set of propositions, we will say that the premises are true only on those occasions when each and every one of those propositions is true.)