Its generally accepted that it isnt because, using reason to justify this, everyone should have equal rights and its unfair for one person to take the life of another. One person may have the opinion that they do have the right to murder someone else but their argument would not be as strong since it would simply be their opinion of the case. Another example could be homosexuality. Many people who are against it claim that its wrong because its not natural but when thinking of the argument rationally, this would mean cars, airplanes and TVs would also be considered wrong since those things arent natural either.
Arguments made using ethics and emotions are not usually consistent and this is why reason is a better way of knowing because it can be applied to many cases. However, sometimes both emotion and reason can be used equally in justifying a moral decision such as when it comes to abortions. According to ethics and emotions, abortion is murder (since the baby is a human being) and murder is wrong (as all lives are valuable and its unjust to take another ones life).
Reason can come in to justify these arguments as well as add the point of the medical complications and effects abortions bring. On the side for the legalisation of abortions, justifiable points includes if the baby has a life-threatening disease or if the mother does that would be pass down and therefore the baby would lead an unhappy and sick life, if the parents are unfit for the responsibility of parenthood (for example, alcoholics, drug-addicts, teenagers), if the mother was unmarried and lived in a strict eligious society, if it was caused by rape and therefore would be unfair to the women as well as cause psychological harm and the fact that the government is intervening and reducing the freedom of choice for women simply goes against basic civil rights. Emotions are involved in the decision to abort a baby because mothers want whats best for their baby and in most abortion cases, the reason behind it is because they feel their baby would not live the life they deserve.
Whether its because theyd spend most of the life in a hospital with an incurable illness or because the mother knows that she wouldnt be good enough for the parenting job. When it comes to making any decisions, whether its a moral one or not, reason should be considered more as it uses rationality and therefore is easier to explain and justify a decision to others. Emotions arent necessarily permanent or consistent and so it would be more difficult to try to get others to understand why youve made a certain decision.