There are four main reasons people often give for why we do not need to treat an unborn baby in the same way as we treat any other person. These are size, level of development, environment and degree of dependency – SLED. Let’s apply the SLED test.

Size – Should a person’s value be based on size? An unborn baby is smaller than a baby after birth. A baby of six months is smaller than a child of six, who in turn is smaller than an adult of sixty.

Level of development – Humans in the womb are physically and mentally less developed compared with how they are for the rest of their life. Should an unborn baby’s lower level of development disqualify them from the respect and protection we give other people? Who should set the level of development needed to qualify as a person? Any level set would be arbitrary and dismiss some human lives for being below standard and unworthy of protection.

Environment – Unborn babies need to live in their mother’s womb for the first nine months of life. Birth is a change of location, not a change in the humanity or status of the baby. Human beings change their environment throughout life. For example, children do not become more human once they go to school. All that happens is that they have reached a level of physical and mental maturity to enable them to cope with and, hopefully, flourish in a new environment.

Degree of dependency – A newborn baby is very dependent on his or her mother or father or an alternative carer. In an isolated area, there may be only one adult who can look after the baby; otherwise he or she will die. We are all dependent on others in different ways and for different things. A high degree of dependency on another person for the basic requirements of life does not diminish a person’s value.

According to the SLED test, the humans who do not qualify as persons are those who are too small, not developed enough, in the wrong location and too dependent on other people. But, in a humane society, none of these are reasons to treat unborn babies differently from people at any later stage in life. The SLED test can be used to challenge people who have a negative view of unborn babies.