This paper is one of several papers initially presented at a conference in March 2020 at the University of Girona, in Spain, in honor of Susan Haack, which will be published after translation into Spanish by Marcel Pons. This paper discusses (i) Haack's important work on proving causation or any other alleged facts, which focuses on case law and academic doctrine in the USA, and (ii) recent important work on the standard of proof in civil cases in Europe collected in Standards of Proof in Europe (Lubos Tichy ed., Mohr Siebeck, 2019). The standard of proof for civil cases in civil law jurisdictions is generally considered to be much higher than the standard of proof stated in common law jurisdictions. In both types of jurisdiction, and especially in civil law jurisdictions, the standard of proof in civil cases generally requires the formation of an at least minimal belief in the truth of the relevant facts, based on the concrete facts in the particular case. Statistical frequencies, no matter how high, will not suffice.