Another scientist, of equal scientific standing, maintains the contrary position. No, in matters of science every person must decide for himself. And even if certain scientific theories are believed to be true, they cannot be binding on the conscience. All human authority, however expert or learned, is fallible, and therefore cannot bind the conscience. Science may show that certain things are harmful to the body , but science can never show that anything is sinful .
Scripture alone can show that anything, for example a particular course of conduct, is sinful.
Natural revelation is a provision of God by which the heathen, who do not have the light of Scripture, may know something of His power, divinity and moral law. It is insufficient for salvation, but leaves men without excuse and provides a standard by which those who lived and died without the light of special revelation shall be judged. This commandment is binding on every man, and the interpretation of it given in the Catechism is doubtless the correct one. It thus becomes binding on the conscience of the Christian to abstain from that which tends toward the unjust destruction of his own life, or that of his neighbor, that is, from that which is harmful to the body. But we should not that the decision whether a particular act is harmful must be made by the individual concerned.