[Question:]{.underline} Is it permissible to baptize a person who is senile or who has dementia?
[Answer:]{.underline} The answer to this question is clearly given in the rubrics of the Roman Ritual. In the section on Baptism of Adults, Rubric §9, the Ritual treats of adults who do not have the use of reason, and makes a distinction. Those who have never had the use of reason, whose condition stems from birth or before the attaining of reason, may be baptized in the same manner as infants, and it is both valid and licit.
However, the question here concerns those who once had the use of reason and who afterwards lost it due to illness or old age. In this case, the resolution is governed by §1, which states that “An adult shall not be baptized except with his own knowledge and consent, and only after being duly instructed. Moreover, he must be disposed to true compunction for his sins.” However, a person who suffers from dementia, and who consequently no longer has the use of reason, cannot ask for the sacrament of baptism. His intention must be, therefore, as it was before he lost the use of reason. If he had the explicit intention of being baptized and sufficient knowledge of the Faith, then he can be baptized absolutely and with certitude. However, for the baptism to be fruitful, he must have had, before the loss of the use of the reason, at least imperfect contrition for his sins in general, without which the baptism will be valid but cannot produce its effect of sanctification, and it would be illicit to administer it.
Frequently, it happens in such a case that there is a doubt about the person’s intention to be baptized, or whether he believed all the truths that the Church teaches. In such a case the Ritual has this to add: “If it is impossible for him to ask for baptism, but has either before or in his present state manifested in some probable way the intention to receive it, he should be baptized conditionally. If afterwards he recovers, and a doubt remains as to the validity of the baptism, he should be rebaptized conditionally” (ibid.). Consequently, a priest will have to do some investigation to elucidate some positive sign of intention (e.g., asking for instruction or regularly attending Mass when lucid) before proceeding with the baptism of a person with dementia.
Answered by Father Peter Scott, SSPX.